back to the original topic, I'd sue for prior restraint and violation of my 1st amendment rights. I would probably also sue for false arrest, as i was doing nothing wrong when they detained me (they can call it detaining me all they want, but if I'm not free to leave, then I'm under arrest, and they can't arrest me unless they have a specific charge in mind when they do). Then I'd seek compensatory damages for the emotional suffering and hardship the traumatic experience caused me, including sleepless nights, fear of leaving my house, and an involuntary flash of terror every time I saw a cop car.
I'd also call every media outlet in town and let 'em know that the cops don't allow people to video tape them anymore. Photojournalists /love/ it when the cops decide our job is now an arrestable offense