IF it's true she was arrested for playing music, and not for -- I dunno -- blocking the sidewalk or something,
THEN the cops were wrong to arrest her.
And IF they were right to arrest her, and she offered no more than passive resistance,
THEN the cops were wrong to use any kind of pain infliction to move her or effect the arrest.
Realizing that DUmmies lie all the time*, I recognize that it is possible that she was actually committing an offense, and that she attempted to assault the cops who up until that point were merely talking to her. I want to hear the charges, and "disobeying the orders of an officer" don't cut it if the orders were unlawful to begin with. And I want to see the bruise or bite mark or cut she inflicted on a cop before any of them tried to touch her.
I care not the ideology, or the content of the music. My reaction would be the same to a rendition of "God Bless America" or "The Internationale."
It is safe to assume that cops lie all the time, too, especially when justifying their actions.