# Building an Agentic Video Editor for Mass Consumer — Ekaterina Deyneka, Reelful AI Engineer · 2026-08-18 Ekaterina Deyneka, founder and CEO of Reelful, presents her agentic video editor as structurally identical to an agentic app builder, with editing real footage harder than generation. At Reelful, users drop in media plus a prompt, and the agent understands the media, proposes a creative plan for approval, then spins up a remote sandbox where agent skills encode cut rules, font pairings, and b-roll generation. Video is composed as React code via Remotion, a verification layer catches composition errors and sends the agent back to reiterate, and the result renders to a polished clip. To hide this complexity from consumers, Reelful is mobile-first with directional templates and a building editor for tweaks. Deyneka demonstrated clips made purely by the agent and announced Reelful's funding from a16z Speedrun. ## Questions this episode answers ### What does Reelful's agentic video editor do? Ekaterina Deyneka says a user drops in photos and videos, adds context or directions such as captions, music, or voiceover, and the agent understands the media, finds the right moments, assembles them, and generates captions, music, voiceover, and b-rolls to return a ready-to-share clip. It can also remove pauses and unsuccessful shots from speak-to-camera footage. [1:23](https://aiengineer.podhood.com/12a562f8-916f-4329-a450-dac90cd8aaf4?t=83000) ### How is an agentic video editor similar to an agentic app builder? Ekaterina Deyneka says both have a prompt interface, a backend sandbox that spins up, and an agent with tools and skills. An app builder works on a codebase, while a video editor works on a video composition. The app builder outputs an app preview, and the video editor outputs a rendered video. [3:09](https://aiengineer.podhood.com/12a562f8-916f-4329-a450-dac90cd8aaf4?t=189000) ### Why is editing real footage harder than generating video content? Ekaterina Deyneka says editing real footage is more complex than generation. With a blank canvas an agent can do whatever it likes, but with real footage it must decide which moments are best, what to omit and use, and how to organize everything. Footage can be messy or incomplete, yet the agent must still deliver a polished, professionally made result indistinguishable from human editing. [4:04](https://aiengineer.podhood.com/12a562f8-916f-4329-a450-dac90cd8aaf4?t=244000) ### Why did Reelful use Remotion for its video editor? Ekaterina Deyneka explains that Remotion is an open-source framework for creating videos as React code, essentially a file listing assets, tracks, and their order. Reelful uses it because agents are really good at writing code, so the agent can create videos with this Remotion framework. [7:06](https://aiengineer.podhood.com/12a562f8-916f-4329-a450-dac90cd8aaf4?t=426000) ## Key moments - **[0:00] Editing is hard** - [0:37] Ekaterina Deyneka: 'video editing is hard... it's tedious, and it's largely still manual' — the gap Reelful aims to solve. - **[1:23] Agentic editing** - [1:23] Reelful's agentic editor takes raw media plus a prompt, finds the best moments, assembles them, and adds captions, music, voiceover, and b-roll automatically. - **[2:46] Infrastructure** - [3:09] Ekaterina Deyneka: agentic video editors and agentic app builders share the same shape: prompt UI, sandbox, agent with tools and skills, rendered output. - **[4:04] Generating vs editing** - [4:22] Ekaterina Deyneka: editing real footage is harder than generating; the agent must pick best moments, cut weak ones, and polish messy clips professionally. - **[5:18] Pipeline** - [6:24] Reelful encodes taste into agent skills: cut rules, font pairings, b-roll selection, plus sub-processes for music, voiceover, sounds, and photo animation. - **[7:06] Remotion** - [7:30] Reelful uses Remotion to express video as React code, because LLM agents are reliably good at writing code; the agent writes the whole composition. - **[7:51] Verification** - **[8:40] Mobile-first** - [8:40] Reelful goes mobile-first with directional templates, letting consumers generate videos without prompts, even while driving, walking, or lifting weights. - **[9:56] Demo** - **[11:10] Beta** - [11:33] Reelful, backed by a16z Speedrun, is releasing its new beta version exclusively for AI Engineer conference attendees, says Ekaterina Deyneka. - **[11:55] Funding** - **[12:25] Outro** ## Speakers - **Ekaterina Deyneka** (guest) ## Topics Agent Engineering, Video Generation, Agent Skill Design ## Mentioned Reelful (company), Remotion (product) ## Transcript ### Editing is hard **Ekaterina Deyneka** [0:13] Hi everyone. I think we can start, uh, but before we start I want to ask you a couple of questions. So, first of all, how many of you took a photo of video during this conference? Please raise your hands. Okay, and how many of you actually posted any video content from it online? Not that many. And, um, to be honest, that was me. I— I was recording a lot of content during conferences, events, trips, meetups, and I never posted them online because video editing is hard. It sounds and it is a lot of work, it's tedious, and it's largely still manual. So, and it also feels like an art and not really automated. And that's why we're building Reelful, and we're trying to tackle agentic video editing problem from, uh, video editing problem from the agentic standpoint. I'm Kate, I'm founder and CEO at Reelful. ### Agentic editing **Ekaterina Deyneka** [1:23] But let's first talk about what agentic video editing is. So, as a user, you just drop in your media, photos and videos, and provide some context. It can be, uh, the context what happened in these media files, or it can be some directions. For example, like add captions, add music, add voiceover, and something like that. And then the agent will go understand your media, uh, find theright moments, assemble everything together, generate captions, music, voiceover, b rolls, and give you a ready-to-share clip. And, um, yeah, so basically, uh, that's, uh, video agentic video editing. So agent does everything by itself. Or another example: you recorded, uh, a speak-to-camera video, and you have a lot of pauses, unsuccessful shots, and you expect an agent to figure it out, to remove unsuccessful shots, remove pauses, and give you a ready-to-share clip. Um, and, uh, the interesting thing is that a lot of— actually a lot of the things inside this pipeline can be automated. And this is exactly what we're doing at Reelful. **Guest** [2:45] Today was the first day of— ### Infrastructure **Ekaterina Deyneka** [2:46] Oh, this is, um, the example of, uh, video edited. And, um, since we're at AI engineering conference, I wanted to talk a little bit about infrastructure. And from the infrastructure standpoint, agentic, uh, video editor is very similar to agentic app builder. Uh, sorry, there is a typo on the slide. So the, uh, second column is agentic video editor. So both of them have a prompt, uh, a UI for prompt, uh, and in the video editor case it's a media plus prompt. And usually on backend, what's happening, there is a remote machine which is called sandbox, uh, which is spinning up, and inside this machine there is an agent with tools and skills which is working on, uh, what you're asking it to do. Uh, in the case of the agentic, uh, app builder, it's a code base. Uh, in the case of the agentic video editor, it's a video, video composition. And as a result, in the agentic app builder, user get an app preview, and for the video editor, users, uh, user get rendered, rendered video. And, but, yes, the, the infrastruc from infrastructural standpoint, it's pretty similar, but there are a couple of differences. Uh, and, um, this is actually the most interesting to me: generating versus editing. At Reelful, we're focusing on editing real footage. ### Generating vs editing **Ekaterina Deyneka** [4:22] So we do not generate a lot of content. We're expecting you to provide your real life, your, uh, personal content, and we will edit it for you. And actually, this is, uh, a more complex problem because if the agent has a blank, blank canvas, it can do whatever they can. But in the editing case, the agent has to figure out, uh, which moments are the best, uh, what to omit, what to use, how to organize everything together. And also, um, sometimes footage can be, um, messy or incomplete, and agent still has to deliver a very polished result, professionally made, so that ideally the viewers of this content don't get if it is like AI or, uh, human edited. So let's actually have a look how we do it, uh, at Reelful. So we start, as I already mentioned, with your media plus a prompt, some directions like how you want it to be edited, and we need to get a polished clip. ### Pipeline **Ekaterina Deyneka** [5:35] So let's go through it step by step. So we're doing first, me- media understanding. We need to understand what's actually happening, uh, on those clips and photos. And we also need to transcri- transcribe speech, for example, in the case if you have speak-to-camera videos. Then we are providing a creative plan for the user so that they can approve if they like it or not, what they want to change or maybe regenerate. Uh, and we create this plan before actually starting editing. Once the user approved this plan, uh, we spin up a sandbox, the remote, uh, remote machine that we already discussed, and this is an environment for the agent to, uh, execute everything. So the agent comes with the skills, and in our case, in the case of, uh, video editing, our skills are, for example, cut rules, how, for example, how to select the best moments. Uh, also font pairs, which fonts are, uh, more suitable for this use case, which are not. For example, how to generate b rolls. And this is where taste and craft, uh, live actually. Um, and then also agent, uh, can, um, can initiate some other sub-processes. For example, generating music that will fit this exact composition, generating voiceover, adding sounds, animating images. Yes, this is actually what we do. Uh, if you provide photos, we can animate your photos to make them more, uh, dynamic and engaging. And then comes Remotion composition. So here a little bit of background. What's Remotion? Remotion is a framework, open source open source framework, uh, to create videos as code, as React code. ### Remotion **Ekaterina Deyneka** [7:30] Uh, so basically it's just like a, a file with the, the order with all your assets and tracks and how they're following each other. And, um, why it is important? Because, uh, agents are really good at writing code, and therefore we can use them to create videos with this Remotion framework. ### Verification **Ekaterina Deyneka** [7:51] And then, uh, the last thing is the verification layer. Of course, agent can make mistakes, and that's why we developed this verification layer to make sure that all the, um, the composition is clean, is well defined, everything will be rendered, and if there, there are some problems, then the agent will, uh, reiterate on the composition. And this is how we got to a polished clip. So it's a lot,right? Uh, it's like a very complex workflow. Uh, and ideally we don't want our users to even know anything about it. And this is even maybe a bigger problem, how to deliver this complex agentic workflow to mass consumer. ### Mobile-first **Ekaterina Deyneka** [8:40] And this is how we're tackling that at Reelful. So we decided to go mobile first so that users can edit videos, videos while driving, walking, or maybe lifting weights. Uh, also, I know that prompting videos can sometimes be also challenging. That's why we create directional templates. For example, like speak-to-camera videos, or maybe you want to add b rolls or voiceover so that users can just select these directional templates, drop their media, and that's it. Even without any prompt, it will, it will work. And the third thing is a building editor. Uh, why? Because we want to make this experience convenient and familiar for users. So a lot of people are already sort of, uh, using, uh, regular video editors, and that's why we want to provide this experience as well. So how it works, user first generates a video agentically, but if they want to tweak it, for example, remove a second or maybe, uh, correct some word in the captions, they can go into building editor and edit it a little bit. ### Demo **Ekaterina Deyneka** [9:56] Um, yeah, and, uh, actually I have a couple of examples here that I recently created with Reelful. Uh, I will play them, just maybe one of that. Oh, sorry. **Guest** [10:08] Last week I was invited. **Ekaterina Deyneka** [10:10] Do, do you hear? **Guest** [10:12] Barely. **Ekaterina Deyneka** [10:12] A little bit. Okay. You just can enjoy the video. **Guest** [10:15] It was, of course, your creators' dinner, and honestly it was one of the best event experiences I've had. First of all, the venue was stunning. It was a custom event space transformed into this tropical sunset feast. The whole atmosphere felt so warm and cinematic. Second, the food was way beyond my expectations. They brought in private chefs from LA, and we had logs, fugue, crop, and this incredible strawberryice cream that I was still thinking about. But most importantly, the conversations were so much fun. It was kind of atmosphere. It felt really easy to connect with people, talk about what they're working on, and just enjoy the community. And lastly, we got gifts. One of the highlights. **Ekaterina Deyneka** [10:53] So, uh, yeah, basically all these videos, they were assembled only using agent, no, uh, regular video editor, and I already posting them on social media, and yeah, it, I, I have a lot of fun with that. And, oh, sorry. ### Beta **Guest** [11:10] Lastly, I was invited. **Ekaterina Deyneka** [11:11] Uh, and exclusively for this conference, we are, uh, giving our better, uh, which is our new, new second version. Uh, please give it a try, uh, and, um, let me know if you have any feedback. Uh, here is my, uh, email, please, uh, feel free to reach out. Uh, we're still early, we're actively working on it, uh, so we will have, uh, we will be happy to hear any feedback and also curious how you use it. And also, um, some exciting news, we recently got funded by a 16z speedrun, uh, so I'm very excited to, uh, continue working. ### Funding **Ekaterina Deyneka** [11:55] Um, yeah, that's it. Thank you so much. And because it's a presentation about content and how to edit videos, I have to, uh, film a video with you all. ### Outro **Ekaterina Deyneka** [12:25] Yay. --- This library is powered by PodHood (https://podhood.com), the podcast website platform.