The original Turing test deals with artificial intelligence: Turing said that AI is truly AI when you chat with someone and from his answers you cannot distinguish whether he is a real person or a computer. Now, I have proposed the Turing Test for DVDs: If you watch a DVD and you cannot tell whether it is the original or a compressed copy, then the copying is succesful.
I ran a few test the past couple of days, comparing the original DVD, the DVD-Shrink copy of it (which takes 3.5 hours) and the DVD-Fab Express copy of it (which takes 20 minutes), both at 50% compression (which is quite big).
In our 92" projection screen, we could barely tell a difference between the original DVD and the DVD-Shrink copy. There is just a little bit of difference, and you have to be watching for the details to realize it. Also, we could not tell a single difference between the 2 copies: both programs work amazingly well.