If you didn't get a chance to check out FloGrappling's coverage of Berkut, this is one match you should watch. Caio Terra pulled off a super sneaky collar choke off the knee slide pass at this past weekend's Berkut Invitational that I haven't seen finished from the half guard. We breakdown the sequence of events:
First Milton Bastos stops Caio Terra passing to left by wrapping a lapel single leg. A lapel single leg is established by grabbing your opponents lapel through their leg and gripping it with your outside hand. In this case, Milton grabs the lapel through Caio's legs with his left hand. To counter this grip, Caio attempts to hit a collar choke by feeding his left arm deep in Milton's collar. But when Caio tries to step over to finish the choke, Milton blocks Caio's leg with his right leg.
Caio Terra then switches to the right side and sets up the same exact choke. To do so he grips Milton's right leg with his left arm and times a jump to pull his right leg out of the lapel grip. Caio lands in Milton's half guard with his left leg trapped. Caio then pushes down Milton's shin shield to get deeper into position and fish his right arm deep into Milton's collar. This time Milton doesn't block the step over and Caio is able to finish the choke and get the tap.
Edit: Here's a video demonstrating the same move but from side control that applies the same principles: