My honest feeling about Den's DVD, which he knows, is that it is too short. However, it is all substance and not one piece of padding. That is Den all over. He is not involved in the martial arts business in anyway and yet he has a tremendous amount of honest knowledge. To begin with he has a degree in maths, 25+ years on the door, 5th dan in Kyukushinkai and much more besides. His comments on forum are notorious for stopping threads dead mainly because what he says is the stark honest truth and also many fear challenging him.
Yet Den, the person, is a very approachable person, generous with his time and I could listen to him all day. In summary perhaps the most criminally under-rated RSBD instructor I have ever known. If you ever get a chance to train with Den grab the opportunity with both hands you will not get a more honest, frank, no gimmicks, no hidden agenda or in depth experience.