Sure, the kid was swinging at the officer, and I suppose that warrants the officer acting in self-defense. But another question is, what are the protesters supposed to do? The government has all the power, and can simply snuff out any resistence. If you just stand in the streets, they really don't care, they are going to take your freedom. Imagine if the US suddenly had a dictator that just decided they were going to…
Do you know about Gandhi's nonviolence and civil disobedience movement ? Not saying this is what's required right now. But ultimately it was that that turned the British public opinion and the Crown was forced to withdraw from the colonies.
Gandhi's first stint at civil disobedience also landed him in jail for 6 years and there was a lot of violence that also played it's role in Indian independence.
Even with an Afghanistan style insurrection it's hard to see China bleeding enough money to give in, so I'm not sure violent means are much of an answer either.