Sadly I dont think i could make one but ive seen peertube and its a bit off feeling( i cant place why) but thought hey maybe those who can make something like that will see the post. (Also I would love to scare youtube with competition cause they freaking need it)
Ill start I NEED to be able to play audio on a Mobile device when the screen is turned off youtube makes you pay for that 1 line of freaking code! Heckin BS
If you happen to be on Android you should give NewPipe a try. It is an alternative client for YouTube and PeerTube as well. It supports managing playlists without login, downloads and background playback.