fyi:
- https://github.com/yt-dlp/yt-dlp lets you download videos (from youtube and also hundreds of other sites)
- for desktop, https://mpv.io/ is free and lets you watch youtube (or any other video) at even more and faster speeds than youtube premium does, among many other features
- for android, https://newpipe.net/ lets you play youtube in the background (and download videos, and block ads, …)
- https://ublockorigin.com/ blocks ads everywhere (and yes it does still work on youtube, at least in firefox anyway)


I noticed that youtube hasn’t let me change the speed at all recently on my computer. They show the typical speed control, but it doesn’t work and shows 4x speed premium.
That being said, I have a browser extension that just lets me speed up the video with a keyboard shortcut to whatever speed I want, so it really doesn’t matter.