Oh I see the Daily Mail have kindly produced a transcript of what she is saying. How ironic that the Daily Mail should come over all high and mighty on racism.
Having seen the video again, I am unclear whether he punches her but he does grab her throat, then he tackles to her to ground and when she tries to get up he pushes her back - head first - out of the bus. The doors close and you can see him step back.
I don't think he should have taken her on - there was obviously a lot going on beforehand judging by the whooping and laughter. He made that situation escalate and then reacted very aggressively. Of course he may fully regret his actions now and may have done so in the heat of the moment, but this clip is not about some racist getting her comeuppance, it's just a sad reflection of our society.