I tried playing a few Youtube songs. It worked perfectly for a few songs. Then it stopped in the middle of a song, skipped to the middle of another song far down the playlist, went backwards through the playlist, and cut off half the time from the songs that it played. So yeah...
Otherwise, the functionality looks good. I haven't had any problems with uploading songs directly from my library yet, non-English doesn't seem to be a problem. and it's nice that you can upload multiple songs in one go. The volume control is also a nice touch, and I like the progress bar.