There really is no acceptable reason for the campus police's actions in this video.
Really, what would have happened if those protesters had just been left alone? Considering how peaceful these protests were, it's hard to ignore the possibility that it was the protesters' message, not their actions, that spurred the police to take such drastic action. I have to say that there really does seem to be a visceral distaste among many law enforcement personnel for peaceful protest. Sometimes I wonder if there isn't some sort of instinctive fear that pops up in those who are empowered by a societal system about those that protest against it -- almost as though once a system stops being accorded 100% deference, it is in danger of being overthrown, not just reformed. Shouldn't a system be robust enough to withstand peaceful protest?