I find them invaluable for group training as in training others in a group without referencing the book. I guess I could scan and print out those sections but I am dealing with children here, 1st to 4th graders.
For those familiar with gymnastics, the DVD's probably are not as necessary, for those unfamiliar with the movements, the DVD's will be a good source to actually see the skill and understand how they move, especially for the multiplane-movement exercises.