nothing you described grants the worker the right to assault the girl. you do not have the right to assault anyone just because...if she suspected that the girl was stealing, she has recourse by calling 911 and/or banning the girl from the store. ask any lawyer, or cop if employees have rights to assault people for stealing.
Did you even watch the video?
Who got hit in the face with a metal tray, the customer or the worker?
At what point did the worker's right to self-defense suddenly no longer exist?
How about when does employees have the right
to defend themselves when they are assaulted?
Granted an ass whipping may not be called for
with a shake being thrown on you. But, attack
with a food tray is different. Or do you lay
down and let someone beat on you?