Elevator Murder Experiment - viral stunt for Dead Man Down

How do you shill a film called "Dead Man Down"? Easy, arrange an attempted murder in an elevator and have people witness it. Film them with hidden cameras as they scuttle away, dial 911 and walk off muttering "sod it, I'll take the stairs". If this isn't staged all the way through, it's a miracle nobody shot the attacker, there are still a select few people that are allowed concealed carry in New York. What if they had run into Robert De Niro, Harvey Keitel or Donald Trumps and his sons?
Ah, that's right, I forgot... In New York City people mind their own business. They'll witness an attempted murder and not tell a soul. Except that guy who seems to be instagramming the whole thing.
So, how does this go viral, exactly? Oh. You watch this and giggle at the people scurrying away. That is until you realize they'd do the same exact thing if you were in trouble. They'd watch you gasp for your last breath of oxygen, while thinking "awkward... how do I ask that guy to press ground floor now? He's totally in the way of the buttons. I'm going to be late. Fuck my life."