THAT, my friends, is called an inside forearm strike to the Brachial Plexus origin. THAT is lights out. The first time I caught someone with one of those, I thought I killed him.
His stance is pretty much Chinese, probably Kung Fu of some sort. He is not very good as it took him a long time to connect. Kung Fu boy is also at least an equal to the Cholo in the aggression. In my jurisdiction, They are both getting tickets for Disorderly Conduct, Fighting.