The traditional arm bar from the guard is one of the more common jiu jitsu moves in MMA Training. This is from the Submissions101 program
Jiu Jitsu Moves from the mount
The mount is one of the most dangerous positions in a grappling fight, if you have someone on you in mount they are on top of you. If you are on top, you are able to work submission holds or pound on their face.
Jiu Jitsu moves from the guard
The guard is my favorite position to work from. You can pull off tons of submissions from the guard, it can also be very hard to escape the guard.

