There is some validity to that but the dude who was screaming had already compromised himself by assaulting the customer.
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The guy filming opens up the video (before the assault) by saying he was already asked to leave.
So does not leaving justify assault? Would it also have justified a homicide?
Get real, the customer at no time presented himself as a physical threat and therefore the idiot behind the counter had zero legal justification to assault him.
Call the cops, sure but assault him, hell no. You know this already as well.
Any other fantasies you want to discuss?