Seems to me that she was taking his complaint seriously towards whoever was driving in that parking lot. For him to hand her the video he'd had to have his hands exposed, while requesting him not to video tape her she notices he put his hands in his pocket. She politely ask him out of concern for their safety to remove his hands, he refuses, she refuses to take his complaint and starts to walk off. He starts to follow them and becomes belligerent towards them...in my opinion she has a right at that point to be concerned about what he could possibly have in his pocket he could harm them with as they try to walk away. To make sure they can leave safely they check him on it. They weren't interested in arresting him for anything, obviously, just to be able to walk away in safety. Doesn't matter he's using profanity and intimidating them, that just raises the bar of them not possibly walking away safely, they secure their passage to leave safely by removing the knife, he continues to be belligerent and demanding but they are leaving just like he requested and even gave the knife to someone else on the porch who wasn't involved in the altercation. They didn't want to harass him, they didn't want to arrest him, they just wanted to assure their safety while there and upon exit. Most cops wouldn't have handled the situation as well as they did. Once he started objecting and tousling with them over the knife they could have arrested him...he's pretty lucky that all they wanted to do is walk away safely, most people would have been arrested.