An NH'er myself, I have noticed that the best riders I see, be they western or english, demonstrate the basic principles of any "natural" philosophy. Whether on TV, or at my barn, the most skilled riders understand how horses (and their horse, specifically) thinks. They therefore can communicate effectively with their horses with limited frustration.. and consequently, without unneccessary amounts of force.
I think NH is all about using the most logical (to the horse!) training techniques and reactions. I mean herd dynamics, like X Branded Heart X mentioned. And this kind of "fair", understandable treatment builds a strong relationship between horse and rider.
Gawani Pony Boy, Pat Parelli, and all the offshoots, understand, in short, that a horse is a horse. And that we humans have a better chance of mimicking a horse than a horse has trying to act like a human. So I second franknbeans (lol) with the three second rule and reacting to dangerous behavior
I also agree that NH can never be captured in any step-by-step DVD. Every horse is different!!