Well from the first slap down or slap up (side Da Haid), we are seeing the open hand deployment of Kyusho (albeit accidental in this case). But this is no different than the Boxing or MMA matches where we see knockouts on Kyusho Targets.
Usually these Slap Fights, last several rounds where the two opponents slap the stuff out of each other. However occasionally a Knockut occurs and it gives us great opportunity to examine and dissect the action to see what Kyusho was enacted.
In this case the bone of his thumb caught the Temporal Nerve and the Zygomaticfacial nerves. Watch the way his head jumps back from withdrawal reflex as opposed to the direction of the powerful attack. But why would or does this cause unconsciousness on someone and more importantly how can we duplicate it?
To learn the method, targets and see the affect in real time, the extended films are located at these links: