There is also this app [1] (shameless plug, I wrote it) which uses youtube-dl to download videos off any supported sites. No real UI as it just parses the media URL (when a link is shared to it) and passes it off to the android download manager.

I threw it together (over a few hours) simply because I like watching stuff on youtube at 1.5x speed and the android app does not allow you to do it (whereas if you use VLC to play the downloaded video, you can increaseplayback speed)

It's also available on the play store [2] with youtube downloads disabled by default

[1] https://github.com/zeronickname/VideoDownloader

[2] https://play.google.com/store/apps/details?id=uk.me.gman.get...