This is stupid. What was the protest about to begin with?
We're to assume that it was racial in makeup because of who we saw in the video?
Him making monkey noises, while out of line, and something a racist would do, doesn't make the event inherently about race.
To explain how this works.
We all know not to make monkey noises as directed towards black people. (there's a lot of history behind it, we'll assume everyone knows)
In a heated situation like he was in -- at a protest where insults are being hurled and people are generally a bit unhinged -- sometimes a below the belt insult might come out.
When you're dealing with a black person in a heated situation (in which you reasonably might be insulting them) it's generally considered a below the belt tactic to use (a traditionally racist) insult like that.
But in a heated situation people say dumb stuff sometimes. And we all have knowledge of these insults when dealing with a black person. (they're in your head as well as mine)
My point being, an even like this doesn't necessarily reflect racists values in the person saying something like this. They may well not live life as a discriminatory, racist, person.
Other possible (not a racist person) explanation: he's an asshole rebel rouser and isn't against going below the belt.
It's important to keep these considerations in mind before we make any sweeping judgements -- he must be a racist klans member -- about a person in this situation based on very limited information.