Many of my "Watch Later" playlist items have been removed, which is why I currently:

1. Vibed a firefox extension that polls my youtube watch later list and saves as bookmarks

2. Vibed a second firefox extension that syncs bookmarks to a self-hosted karakeep (bookmark manager)

3. Configured karakeep to download videos from youtube bookmarks (it uses yt-dlp internally).

It's pretty nifty.