I like this approach and that it's so flexible and approachable. My nit for the site would be to explain it a bit better - it's a bit hard to grok with everything going on until I went to the repo. There's also opportunity for non-tech users here just using the agent skill but I'm not sure they'll understand the use if they read through the site.

I had made a skill for something similar to use just HTML5, Canvas and JavaScript, and export the video to MP4 (https://github.com/siegerts/skill-canvas-video).