Actually, the militarization of U.S. police forces is a legitimate concern. A lot of police jurisdictions are getting military-grade hardware from the U.S. military, as the military is trying to unload a lot of it's surplus from their wars in the Middle East, and a lot of police forces are eager to get their hands on it. This ranges from small arms and non-lethal hardware (NV and the likes), to fully armored vehicles.
Anecdotally, the city I live in recently received a tank and several armored transports for their police force. The tank is obvious overkill, and I'm pretty sure they gutted it and keep it for show, but the armored transports are designed to withstand sniper fire and IEDs, and have a nest on top with a machine gun. They occaisionally drive through downtown in them. I live in a college town with only a couple tens of thousands of people, but you'd think they were anticipating a full-scale war from half the populace.
Also, the Ferguson police have supposedly been harassing members of the press and actively interfering with their work. They have tear gassed an Al Jazeera T.V. crew and taken down their equipment when they fled, they have arrested reporters for little reason, most recent their arrest of two journalists who were trying to charge their batteries at a McDonalds (with permission), and they have fired on the press with no warnings, often damaging their equipment. Regardless of the state of investigation, their actions have been unproffessional at best, unconstitutional at worst.