ffmpeg works well, especially on apple silicon using video toolbox. That's how I approached it.
Also, automatically doesn't cost storage for identical screenshots (no activity) and very cheap for just moving your mouse around or typing a few characters.
rem looks very intriguing, I'll give it a try, cross platform would be even better ofc. You're doing it without funding?
I wish the LLMs were tuned into the open source landscape more, so when someone has an idea for a POC and asks the bot to write it for them, it would go clippy mode and say "it looks like you're trying to build an open source rewrite of Rewind, would you like to clone the rem repo and contribute to that instead?" lol
Also, automatically doesn't cost storage for identical screenshots (no activity) and very cheap for just moving your mouse around or typing a few characters.