Facts wallahi, he is lucky that he has true friends like that (not saying what he did was right, that was a pussy move to hit someone in the head like that whilst they were on the ground, but he saw his friend getting banged up), in this era of social media and fakes. Most of ''these friends'' would have just laughed and watched him get banged up.
That kid was an idiot for not having his guard up or at least trying throwing a punch back, I mean, even when he went to the ground he didn't even attempt to fight back. I hate people who sucker punch too, but then again its a street fight, and not a boxing fight or cage match where everything is guarded by certain rules. You have to be ready at all times. The black kid, should learn from this and take up an MMA class. He is young, so he can learn quickly.