Along with Star Wars, Harry Potter and the Deathly Hallows and Scott Pilgrim vs The World are treated to something called “face-folding” and high-pitched voices. The end result is hard to explain, other than to say it’s ridiculous, funny and terrifying all at once.
Creator “iZacLess” mentions on a similar video close to the same length that the process took about eight hours, though he doesn’t go into detail about exactly how he went about it.
We can guess, though. Maybe he loads the footage onto DVDs and runs over them in his car? Yes, my knowledge of video editing is somewhat lacking.