On Android I’ve tested SkyTube and NewPipe and my conclusions are that for playing videos in background (audio) the former is much better than the latter.
As for desktop, I tested many solutions, but for my purposes only a few were workable:
- “Easy Youtube Video Downloader Express” firefox plugin: works well but has some limitations in free version; it also doesn’t allow downloading multiple videos (like yt channels/playlists) on one click
- “Any Video Converter for Mac”: in general works well but sometimes it has problems and again, it doesn’t support yt channels links for multiple videos
- “youtube-dl”: the only disadvantage (for some) is that it’s command line tool written in python but besides that there are only pros and it’s the best of all tools I’ve tested; it can download multiple videos on one link (yt channels/playlists), you can download subtitles/descriptions/thumbnails, you can choose resolution, you can freely choose the output video/audio format and lastly it supports not only youtube but also other, known video services like vimeo and others. For those not supported websites, if you are technical enough to locate a video stream url in browser developer tools, you can use it with youtube-dl to download a video file. The program is actively developed so if Youtube team make some changes to the protocol, to cut off those video downloading tools, the ytdl team has a fix in a matter of hours.