It depends. If you're having a hard time with certain training aspects, it's nice to be able to see it. However, you are going to get WAY more information out of a well written book than you are out of a tape or dvd.

No matter which way you go, get on a program of "progression" training, where everything the dog is about to learn is based on what it has already learned. That's what I like best about the Smartwork books.