youtube-dl is still under development (last commit at the time of writing was 2 weeks ago), but there are forks with more features, such as yt-dlp.[1]

[1] https://github.com/yt-dlp/yt-dlp

yt-dlp[1] has now taken on that mantle. I think mpv nowadays just recognises yt-dlp as the de facto alternative, but if yours doesn't then you can just put this in your mpv.conf:

    script-opts=ytdl_hook-ytdl_path=yt-dlp

[1] https://github.com/yt-dlp/yt-dlp