First he had us work on hopping from side control to knee-on-belly. A couple of points about side control. You want to control the head and control the hips. I notice that he grabs the far pants leg underneath like a lot of the higher belts do. That does a great job of controling the elbow escape. Mamazinho made the point also that if you don't have control over the hips with an arm, then you need to move your knee up higher to block the hip.
For the side control to knee-on-belly transition, you want your north hand to grab the collar behind the neck (first half of the baseball choke, by the way), and your south hand to grab the far pants leg underneath. Move your south hand to grab the belt and slide your south knee against the near hip. In one move, hop up to put your south knee on the guy's belly right where your south hand was. At the same time, slide your north leg 45 degree out for stability and base. Your north leg should be around the same level as the guy's head or shoulder.
Mamazinho showed us a simple armlock from the knee-on-belly. Basically, it is an attack you can use if the guy makes a mistake and tries to push you away, extending his arm and pushing against your chest. If the guy does this, grab his arm near the wrist or forearm and swing your north leg down and over his face. Tuck your south leg under his armpit and squeeze your knees together. He's now in "The Web". Drop back carefully to complete the armlock.
He also showed us a better way of escaping knee-on-belly than trying to push against the guy's chest and inviting an armlock. It is better to take your outside hand and push against his belt or midsection. This will extend the leg that is dropping the knee and make it more vulnerable to attack (just like an extended arm is easier to attack than one that is tightly bent). At the same time, grab the foot with the inside hand and continue straightening out the leg somewhat. Elbow escape your hips away from the top man, but as you do this come up on your inside knee. It sounds more complicated than it is. Essentially you want to end up with your inside knee on the ground and your outside leg posted out--as if you were doing knee-on-belly with the mat. Use this leverage to push the guy back, using his leg as a rudder to drive him over.
Lastly, Mamazinho had us work on hopping from one side to the other with alternating knee-on-belly positions. This is what gave the afternoon guys a hard time and those of us in the evening were little different. I worked with Andy from New York (who got his blue belt last night just before heading back to the east coast) for most of the drills, but eventually switched over to Bruce (the barkeep). He'd been in the afternoon session the other day and helped me figure out some details about how to make the switch work.
Basically, as the guy turns into you to elbow escape or go to knees, you want to replace the knee on the belly with the knee of the leg that is posting. It should be as much a simultaneous process as possible. You then sink the armlock from (almost) behind the guy as he is turned away.
I think this is one of those moves that is very simple, but looks very impressive when pulled off. In most instances you won't have to switch back and forth 50 million times. One switch, maybe two and either you've got the armlock attack or you don't.
