Here's my reply to your post on the other board:
I don't know where you can get the DVD's used but you can get them new at the NPA
If you want to learn Tom House/NPA stuff, then the best way to do that is to attend one of their camps. But if that isn't an option (they ain't cheap), then the book and/or DVDs might be worth it. I have the book as well as the "Pitching Mechanics" and "Performance Drills" DVDs. These two DVDs are redundant with the book however some people learn better by seeing and hearing as opposed to reading. The DVDs are nice from the standpoint that you get to see pitchers demonstrating things instead of looking at still pictures. The book is the least expensive route.