From the beginning of the video, you can see the injustice the police distribute in Denver, Colorado that day. These protesters are doing what every group of peaceful picketers have done since the demonstrations of the 1950’s and 1960’s…they are standing their ground and are well within their rights in doing so.
These various political activists were marching toward the Democratic National Convention Center in a peaceful manner. When they approached the building, the police (already unnecessarily donned in riot uniforms) trapped the large crowd on every side with the buildings behind them so that they couldn’t escape. The crowd was well within their rights to continue up the street when the Denver policemen initially began to enclose them, and one of the worst things about videos like this is that with all that gear on the actual officers can’t be accurately identified.
The cops probably anticipated the hundreds of video cameras and phones from the large gathering of protesters. It’s either that or they really did already plan to corner the crowd (provoking them to try and continue to walk up the street, thus inadvertently “approaching” the police) then use the gas and pepper spray on them. Luckily, there was one focused news team and many other watchers there to catch and report this horrific scene.