Matt Darcy teaches the juju-gatame arm lock when your opponent cross posts to stop the crash sweep from closed guard. The juju-gatame arm lock can be done from numerous positions and is a staple in Guerrilla Jiu-Jitsu.
Instructor: Matt Darcy
Location: Guerrilla Jiu-Jitsu San...
Dave Camarillo goes in depth on a powerful armlock from top half guard. This is a Dave specialty. Dave aggressively pins the undertook and steps over the head. He then threads his leg under the arm to make a V o n the half guard leg. To finish he fulcrums the arm out of the defense.