SXSW Bully sucker punch. Justified or cheap?

Broadmoor74 said
What a great video. While most by-standers are either entertained by the situation, or are too pre-occupied with filming it on their iphones, or are too drunk, or are too timid to do anything about it; the puncher knows early on that HE'S going to do something about it, even though he clearly looks uncomfortable with the situation.

Notice the guy who got slapped in the face, tried to kick the bully in the nuts after he'd been knocked out. That probably takes it a little too far.

For my two cents, the guy that kicked him in the nuts is probably the only one that had a dog in this fight. The guy that hit him first had no business in it at all, sure the guy probably deserved it(we don't really know how it started)but the guy that did it, did not have any business doing it.