I have my suspicions this was staged, theater. For one thing, why on earth would anyone just so happen to be standing there filming this "preacher" in the first place? US sidewalks are littered with such people, ten a penny and so it seems like rather a steep coincidence that at that very time someone would come along and brandish a firearm (almost certainly a felony in any state) all while being filmed.
Furthermore what is he "preaching" about? what is his goal? Surely he should be focusing on the gospel not alienating the very people he seeks to influence by telling them how "wrong" they are.