I wanted to give my phone to a young disadvantaged kid so that he can watch educational videos in his spare time from youtube. At the same time, I did not want him to be wasting time on internet or youtube.
So I used Kids video player to allow him to play only the videos that I load. This app uses another app called Kids place which is essentially a way to enable some apps to accessed only once the a password is added.
When working in tandem with Kids video player, Kids place will block the search youtube feature in kids video player until a password is added.
Thus, the kid will only be able to play the playlist that you want :-)