youtube-dl from git no longer available

The latest version is available on the official website, where you can download the tar.gz file (v2020.09.20). On the homepage, there is a message: "Currently our dev repository is taken down due to DMCA takedown notice by RIAA. Downloads still work as usual."

The widely used fork youtube-dlc is still being actively maintained.

It's probably a good idea to switch for the time being because the September release from youtube-dl.org is already bitrotted and doesn't work with YouTube (and possibly some other sites) any more. The most recent youtube-dlc release (dated today) does work.

It looks like youtube-dlc has removed the tests that were used as a pretext to take down the main repository. Whether that means they're safe, I couldn't say.

You could try this. This was in the readme of the original repo.

sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl  

This updated my version to 2020.09.20. Maybe that'll be enough for you.