Last training before the tournament ... no gi ... Mamazinho showed us a nice move from the mount. Actually, it's a counter to when the guy on the bottom gives you his back as he tries to turn and escape.
The idea is to let him give you his back if he is going to make that mistake. Stand up a little bit to let him roll and then drop down, jamming both hooks in.
Pick a side. Reach under the armpit and grab the wrist.
Pull the wrist in towards his body, and do a shoulder roll toward that side.
As you roll, the guy should be especially susceptible to the mata leao/rear naked choke. With your free hand, reach around and set the choke around the neck.
Let go of the wrist and lock the choke with that hand/arm.