why do they refer to him as a mentally challenged man?

dang it.. that video pisses me off. i thought karate was about discipline. the dude from the dojo clearly just got frustrated at how he couldn't land a hit and the other dude was staying calm, and keeping up a superior attitude.

but man thats messed up when he starts kicking his face in..

and the showing of the trail of blood just infuriates me. thats just impossibly messed up.