If you were thinking of buying this product, as I did, and as I have all the annual "Best of" DVDs dating back to 2007, I have some advice for you.
Do not buy, or support this bullshit. Why? The main feature and first disc, on both the DVD and BluRay is a 2 hour highlight reel. Only Cain-Dos Santos and Silva-Leben are shown in their entirety. The second disc is full fights, thankfully, but none of them are really "extras," it's just full versions of the highlight-featured fights on the first disc, which should've been full length in the first goddamn place.
Someone did the math on the Amazon reviews page, and the DVD includes 22 full-length fights (when the cover brags 30). Compare previous year "Best of" offerings:
UFC Best of 2008 - 11 full fights
UFC Best of 2009 - 26 full fights
UFC Best of 2010 - 38 full fights
UFC Best of 2011 - 22 full fights
I'm really disappointed. For the complete lowdown and a theory on why the UFC did this, check out a really good review I found on Amazon.
EDIT: It also seems like the UFC is stepping up the editing after the fact. For example, Joe Rogan's complaining about the Cung Le-Wanderlei Silva stoppage is completely edited out.