MeTube is a yt-dlp based docker container that sets up a localhost service for downloading video/audio from YouTube and a huge number of streaming video sites. It lets you download whole channels, individual playlists, and extract the audio from streams. PinchFlat is another option, but I haven’t tried that one out.

ytmate.com is a decent online web side for downloading individual files.

Links:

• https://github.com/yt-dlp/yt-dlp
• https://github.com/kieraneglin/pinchflat
• https://github.com/alexta69/metube