I've found myself annoyed by the fact that Youtube doesn't have a playlist feature whereby a user who wants to, say, listen to a bunch of songs on Youtube, can have them play automatically, not have to go back to the Youtube window and select the next video to play. So I've made this app for myself or anyone else who wants a series of Youtube videos to automatically play.
In the list on the right, add in order the IDs for the Youtube videos (Ex. https://www.youtube.com/watch?v=sMqNFAU0tOw has ID sMqNFAU0tOw) that you want to view consecutively, then click Play Videos! Your videos will play below, one after the other.