I watched the video. Something was already going on, someone was being bullied by that crowd of “children.” The man intervened. The crowd reacted aggressively to him spoiling their fun. Some individuals in that crowd even assaulted him, from behind. First. Before he shoved anyone or threw a punch. One particularly aggressive not-so-little girl got in his face. He pushed her back. She came back at him. Then he threw the punch.
Was he wrong? Maybe, but at what point? He was certainly not “totally wrong.” He does not appear to be a “dangerous man assaulting children.” They appear to be assaulting him.
The video record provides him with plenty of excuses. Was he wise? Probably not.
A lot of the interpretation of his actions is going to depend on what that crowd of children were doing before he tried to break it up. Were they hectoring, or even physically threatening some one, as it appears? Who?
What was the adult’s relationship to the apparent possible victim? Who was/is ‘Emily’? What was her role in the activities and actions taking place before he intervenes? What did HE see that led him to step in in the first place?
There is always more to any story.
The individual who pushed him in the video is the same girl that got knocked out because no one else was wearing black like what she had on.