She blatantly used that silly string shit and sprayed it at them in addition to someone behind her throwing water..
You can talk all you want and blabber on about stupid crap but once you engage them physically, for the most part it's fairly easy for them to use force to respond within the confines of the law..
VIDEO
This is CLEARLY a case of police over-reaction and a situation of GUILT BY ASSOCIATION. If you slow mo through? the video you see an unidentified person toss a form of liquid and then as the woman approaches the police says something and turns around starting to walk away.
Mr Police Officer turns around, sees her with drink in her hand, ASSUMES she tossed the liquid, this video is really going to help her in her lawsuit vs the city of Philadelphia...Good luck defending this one Mayor Nutter.