After watching that video I’d say your life was in danger the minute that mob of “youths” entered the store. That is a scary scenario.
That’s part of their “training”, to intimidate and confuse.
There was a video a while back of some “urban youths” beating up on a blond girl in the subway.
The attacking girls were doing this “screeching” thing that someone explained was intended to both disorient the victim, and confuse anyone that was tempted to help the victim.
This is really strange, describing attack methods and tactics like you would as a wildlife observer.