I really like this :)
I've been looking for something like Twitch Alternative Player for other sites for a while now and this seems to work well enough for what I've done with it so far. For youtube specifically, it would be really good to be able to make it Theater mode and if videos started by itself (right now I have to press the play button after the site loads), I might use it as default if these things are implemented. Thank you for the extension!