I don’t fault the security guard for not assisting. Who knows what kind of training she has, and likely wouldn’t be covered if she were injured by a flailing suspect.
That said,recording the arrest is just low-class. Shouldn’t be doing that while on the security job either. Use the phone and call another cop.
To be fair when I worked security my company did not want us to touch or manhandle anyone for fear of being hit with a lawsuit, observe and report was our job, however videotaping in this regard was classless I agree.