If you watch the video you're referring to a little closer, you'll notice both during and for a second or two after the tires chirp that his brake lights were lit up.
Not sure why he would hit the brakes if at this point he had already made the decision to plow into this crowd.
Another curious observation of this video is in the audio. At this same point, you already start to hear blood curdling screams begin and a slamming sound of some kind, which all happens before the first protestor with a stick or bat hits the driver side taillight area.
I'm not trying to argue the guy is innocent of anything, but not everything seems to cleanly add up to this being premeditated either.