This is certainly thuggish behavior, and it's not my intention to excuse it - it's really not excusable. I also believe police should be subject to publicly created record while performing their duties when other conditions do not prohibit the creation of that record (i.e. if they are in a restricted area, the public should not be expected to be granted special access for this purpose).
However, there is a mass education issue at stake here. A number of these police video recordings are misrepresented when released on YouTube / whatever. They show partial truths. We should always demand to see the video before and after the incendiary incident, and we should reserve judgment until we can see all the evidence, not just the cherry-picked clips that look worst.
For example, the UC Davis occupy students who were pepper sprayed by a cop while sitting peacefully. It turns out, those students were no longer protesting Wall Street, they were protesting the arrests those same police officers had previously made of some of their friends - who were arrested not for protesting, but for interfering with police action (removing tents on the quad). On a larger scale, they were blocking police progress, they were encircling the police officers, and were telling the police officers they would not let the police go until their friends were released. A small group of the officers had been separated from the rest of the force and were being detained by the crowd of students. The police were being antagonized and borderline threatened. The police issued multiple warnings that they would soon start using non-lethal force, including directly to that group of students. The officers who did the spraying walked up and down the line which blocked their progress and informed the students that they were going to be subject to increased force, and gave them an opportunity to allow the officers to pass. The students were only sprayed after they continued to refuse to release the officers.
Whether or not you agree that pepper spray was the appropriate response given the fact that the students were creating a very hostile situation by encircling, separating, and detaining police officers for reasons not related to their protest, the fact is that these fairly important facts were not represented in the videos which shot around the Internet in the aftermath. Personally, I think that if you're going to separate, surround, and detain police officers, you're lucky that pepper spray was the only result. That kind of situation could escalate in a dangerous manner very quickly (both for the officers and for the students) if they didn't get control over the situation fairly quickly. It would take only one student to throw a rock at the officers, and mob mentality could take over. The worst of the outcome being some pepper burns is much better than other outcomes that could have precipitated from that scenario.