I have several Instructional DVD's in my collection and I like them all for different reasons.
I have 2 from Mike Portnoy: Liquid Drum Theater and In Constant Motion both are excellent! I am looking to get his two latest DVD's as well
I also have a great one from Greg Bissonette, one from Billy Cobham, and Carter Beauford all three of these are great as well. The Greg Bissonette one is excellent and covers a great range of techniques that anyone can do with practice. Although he is quite a talented drummer and makes it look easier than it really is

I am anxiously waiting for Mike Mangini to come out with a DVD!! I have some of his teaching materials and he is quite excellent. I saw his twice at clinics and of all the clinics I have attended, none have made me want to go home and burn my kit and give up more than his LOL

Of course I am joking, his ability to play with all four limbs as independant entities is amazing and awe inspiring! You go home from his clinics pumped up and ready to move to Boston and study under him at Berkley.
If you haven't seen Mangini, do a search on you-tube. There are a few decent solo clips there that are just crazy!