So the new video shows that police attempted to assault (unlawfully arrest) American citizens engaged in the clear exercise of First Amendment rights. The police repeatedly announced to the citizens their intent to assault them if they did not cease exercising their protected political rights. The police subsequently began manhandling some citizens and continued threatening them. The police then cleared the tents and detained some citizens in the course of that (assuming the commentary on the video is accurate--we know at least that some people were detained). The citizens then demanded that the police release the American citizens they had unconstitutionally detained, and blocked a car path.
The police were never prevented from leaving. That is nonsense. They were free to leave any time. They freely chose to stay, and they freely chose to assault more American citizens. Contrary to the implication of the commentary on the video, telling citizens in advance that your intent is to assault them does not give rise to cause for an assault. Even if one believed that force was justified to clear the path for the car (and I don't), the requisite amount of force would be no more than required to clear the path, i.e., human arms to lift up bodies. If the police felt they were outnumbered (and there is no evidence of that), then the appropriate response would have been to call more officers to the scene. The video in no way justifies the pepper spraying.
In the end, it was the police's (and, presumably, the dean's) decision to repress a peaceable assembly of Americans that resulted in the violence. The blame lies squarely on them. The commentary to the video posted takes a decidedly authoritarian slant in which the prerogatives of police are placed above the prerogatives of American citizens. It assumes the legitimacy of the police's presence when the reality is that their presence is the first provocation and threat of violence.