Sorry just got around to checking. It has to be a direct download URL, like a download link to an mp3 or something to work. No real easy way to do this through YouTube and it's actually against the terms of service to try and extract the audio from its videos. But maybe if you have a download link to a SoundCloud song that would work? It's not a very useful feature I admit XD. Sorry for the confusion.
WebGL based planet generator featuring a quadtree level of detail system
Play in browser