Sometimes with a cellphone arrest video, you'll see cops behave bizarrely, shouting things like "stop resisting!" or "gun!" when it's obvious the suspect is not resisting and is unarmed. The point of it is to establish, on less revealing recording devices such as bodycams and dashcams, that the officer has a reasonable fear for their lives. That fear is thought to legally justify anything bad that might then happen to the arrestee, even if it turns out to be mistaken. And so the weird yelling about guns and resisting becomes a ritual to that end.
Which is to say, if a cop starts shouting "gun!" during an interaction with you, that cop intends to kill you and you better get lucky fast.