http://www.youtubedoubler.com/
nice site , play 2 Utube video side-by side, so you can mash up video .
you can set delay to videos to better syncro them |
DPic
Hah! Nice combination! |
=]
Not sure who came up with it but i got it via Reddit http://www.reddit.com/r/reddit.com/comments/ag76d/usher_goat_best_mashup_ever/ |