There's also a new extension that was posted on hn a few weeks that's free and claims to have scriptlets to block youtube ads as well: https://news.ycombinator.com/item?id=43204406#43208085

You can perform video search through DuckDuckGo, Invidious, or Piped.

The latter two are often blocked themselves, copy the video URL and feed to mpv to play through your preferred video player on the command-line:

<https://mpv.io/>

Recent mpv / ytdl can almost always gain access. If you are blocked, check for updates to ytdl (which mpv typically uses for video/media downloading).