Last November I attended a march/protest sponsored by Occupy St. Louis - to take photos. Yeah, I'm mad at the 1% too, but public protest is not in my genetic makeup. However, it was pretty fun and exhilarating, and in order to get a variety of shots, well, I had to join the fray at some point. ;-)
The crowd of about five hundred marched from Kiener Plaza to the Martin Luther King bridge, hoping to shut down traffic and make a point. The cops were ready, as you saw, and about seven or eight protesters were clearly ready to be arrested. It was a peaceful confrontation, however. =)
All in all, an interesting experience, glad to have had it.