Keep your eyes on the guy in the grey shirt on the left side of the frame. He's just hanging out, watching afro guy strut around and slap people like a prick. He does not like what he sees.

And then our villain decides to punch a poor man who looks very much like a young Colin Firth, at which point grey shirt decides that he has seen enough of this bullshit. Street justice ensues.

h/t Hickey