I must confess, I've never understood the difference between the "Gangsta Lean" and the "Monkey Mount". I know there's a move I attempt often where you mount the opponent high and off to one side and in my mind, I alternate the name of the position between those two moves. In any event, the position is broken down in Eddie's "Mastering the Twister" book.
It's interesting to see Ryon using it at the recent Gracie Worlds. If the video doesn't start at the right place, you should jump to 6:02.