Quote - right or wrong, I see some lawyer getting rich off this.

First, if he was the police, they're required to identify themselves.

Second, if he was the police, roughing up a perp, especially in front of witnesses, would leave enough holes for the defense to drive a semi through..

It could serve as a bad example on how (not) to apprehend and arrest someone...

He wasn't a police officer. He was a paid store security guard "under cover." 
The police were called and showed up after that guy took her inside in handcuffs, but he wasn't a police officer.

However, I sure hope that she sues him for damages. I'm sure she's got broken bones and multiple abrasions and contusions all over her body. I'm not exaggerating when I say he was roughing her up and throwing her to the concrete with what looked like full force.

I don't care what her crime was, he didn't have any right to use that kind of force on her.  She weighed much less than he did, she didn't have a weapon, and yes she was trying to run away, but so would I if I had some guy jumping all over me and throwing me to the ground head first.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi