1) This appears to be a university and the crowd consists of youth.
2) There are students who are purposely blocking a road/walkway of some kind, possibly preventing a police cruiser from driving through.
3) The students get pepper sprayed while sitting and then arrested.
I can't for the life of me understand why the police felt the need to cover students with noxious pepper spray before arresting them? As you can tell from the video the reaction of the onlookers was rather immediate and galvanized everyone against the police. While the video eventually turns into the typical OWS chanting it seemed pretty clear that there was quite a bit of tension as a handful of officers armed with more pepper spray and non-lethal weaponry were surrounded by an angry crowd.
This seems like excessive at best and potentially dangerous at worst. If this is indeed a campus and not a public street/road used for traffic then the action of the police offers is inexcusable. If the police felt the need to arrest them, then arrest them, but this is just fuel for a fire that will burn hotter and longer once the economy inevitably double dips.