Some call it the Gator roll or bulldog or ventriliquist. Its huge in wrestling off a good sprawl or snap down if you get good at them. Although it looks like this guy hit it with an underhook instead of trapping/pinning the arm to the body. I found more success setting them up like a gator roll to an anaconda choke with locking in the arm triangle(for wrestling). Grabbing the chin a twisting the head is the best part if you dont set it up like a gator roll.