Instructional dvds can never replace in person instruction but can give you a few ideas. Problem with this is that you may try techniques above your skill set and thus risk injury. I see it all the time where people want to pull off new moves and wind up injuring themselves or others. It's better to master the basics that try to learn a slew of moves. That said if you got at least a year under your belt they can be of some benefit.
Bas' Big DVDs of Combat is a decent all around instructional. Some of the techs don't work very well though, like his buck and shuck backdoor escape from the mount. Better off trying to sweep.
Karo has a decent Judo for MMA, it's more helpful to prevent Judo techs as employing them is a different matter.
Rodney King's set is ok, the monkey defense is especially good if caught off guard.
Schrembri has a decent omoplata set though hard to pull off.
Marcelo Garcia has several bjj but are more oriented toward sport jiujitsu.
There's various instructionals on the various types of guard, dynamic, rubber, half, sitting-up, spider, butterfly etc. Kesting has a decent dynamic guard, Eddie Bravo is the pioneer of the Rubber Guard(though IME it's hard to employ in MMA) and Mauricio "Tinguinha" Mariano has good spider, cross, and sitting-up guard instructs.
There's plenty of all in one sets too like Renzo and Kukuks, Kukuk's A-Z of BJJ, Daniel Moraes, Saulo Ribeiro, Gustavo Dantas, etc. In the end most are just flash moves that won't work except on the inexperienced. Most are sport jiu-jitsu oriented and don't transfer over to mma unless you like getting your face bashed in. I likely have over 100 instructional dvds but haven't watched any in over a year because they just can't replace the actual experience.
