There are many great BJJ fighters and teachers with DVD's on the market. Demian Maia is among the best. Demian covers details many do not and does a wonderful job and providing different looks and the reason you do certain things. Great as a reference and to go back and clean up your technique. There are only a few techniques here and there that I didn't already know, but Demian reviews those little things so well there is still much to learn from all of the material.