This is a feature request which I think would be really cool and useful, although I know it's probably not gonna happen fast ;-) Currently it's quite awkward to catch up on videos in a long watch list. If the app used Google's YouTube playlist API to create a personal playlist of all videos on someone's watchlist, this would make it possible to use the YouTube app to watch all videos in a row without having to find each one individually. And with YouTube Premium, the whole playlist could be downloaded for watching offline on the long journey back home :-)