Assumption #1: the guy in the USA a jacket is a drunk trouble making scum bag who intended to physically harm the peace officers. He deserved it.
Assumption #2: the cop was a power hunger punk who too eagerly stomped on some guys civil rights and escalated violence. The cops abused their power.
It's amazing how we see the world so differently.
My proir knowledge and experience with local police has me leaning toward #2. I only wish there was a camera following this guy after he was led away. SOP is to take guys like this to an emergence room instead of jail.
Anyway, the details are beginning to emerge. Apparently, 5 or 6 "rowdy college students" in the section in front of Mr USA were ejected prior to this incident. While looking for more trouble makers to eject, the security guard in the video was standing in front of Mr USA's section and blocking their view. While many people in the section began heckling the guard, he singled out Mr. USA to eject. (Perhaps he was the loudest, closest, ugliest ?????) The two began arguing. The crowd chanted U-S-A, while the guard called the cops. (real Pittsburgh Police) A cop arrives and finally gets Mr USA to leave and we see the rest on the video.