“One of the news articles I read said that several of the officers were wearing body cams, including the first officer on the scene.”
One more piece of evidence of the kids mistaken stupidity. They all think that they are going to be able to get the cops to back down and go away once they pull out their iphones.
It doesn’t even occur to them that the cop has been filming THEM the whole time. The cop knows everything he says and does is being recorded from the moment he gets out of the squad car. He presumably believes that his body cam is going to show how out of line the kids are. Not how out of line he is being.