A sophisticated counter when you are pressed against a wall

If your opponent merely tames your hands, you can defelct them by rotating your waist as you execute a counter-strike. But if he is gripping you, you have to release his grip. It would be easy if you can move back a step to release his grip and simultaneously counter-strike. Suppose you cannot move back, like when you are being pressed against a wall. What could you do? Here Grandmaster Wong demonstrates a sophisticated counter.