As far as I can tell, they're just a bunch of punks who are causing damage and rioting for the sake of causing damage and rioting under the false pretense of standing up for something.
Actually, the majority of the demonstrators were peaceful. There were multiple groups there, including anti-war; basically anyone who is sick of being screwed over. If you think that sending the military after people is a good idea, then you need to read from Infowars every day (study Posse Comintatus while you're at it).
The G20 in Pittsburgh is only there to screw Americans over. Once they create an international currency and kill the Greenback, then the U.S. economy will be no more. It will just run on war, private prisons and riot police.
@everyone: But hey, feel free to call me a conspiracy theorist.
Support bacteria -- it's the only culture some people have!