It’s a miniature class prank in motion, aided by the instructor in the brown belt.
Many of his arm and leg movements, seem to nullify force, rather than fighting his opponent. Instead of force against force, it’s leverage that bypasses incoming force and diverts/negates it. That’s something I’ve also felt at that range standing up, when opponents try to cross into grappling range past my arms. Even if I can’t out wrestle them, I can still stop them from closing the range by using my arms as levers stuck to the other person.
The vid had some useful training tips at the very end.