I'm pretty sure it was in the "The Largest Gang in America" video on youtube. It is basically an hour long video of the cops doing shitty things. I really makes your blood boil. I think the video got broken up into 6 ten minute sections, but here is the first one and I think where the scene I was talking about happened. I could only stomach a few minutes of the video though.

http://www.youtube.com/watch?v=gH9k8L3oDa4