A more controlled arm-bar attack sequence from mount.
Establish a high mount, knees under the shoulders, squeezing them together to expose the opponent’s arms. Cup the back of the opponent’s head and lever it up to compress the opponent and apply more pressure than with just mount. Switch to an s-mount position using the head control to help get the right leg in position, and keep the left knee under the opponent’s shoulder. Trap the arm on your left with your left arm by reaching across and grabbing your right thigh. Make sure all your weight is on your opponent’s chest, and you’re sitting on the floating ribs. Remove the right hand hold on the head and grab the opponent’s knee, reaching around to grab the leg on your left side. Drive it across to your right side and to the ground. Keep the knee pinned and use this for balance. Bring the left leg over the opponent’s head, remaining started on them. Get a proper grip on the opponent’s arm now and apply the arm-bar while still sitting on the opponent (if possible).