Watch this. And never doubt again that it only takes a moment in time for something completely unplanned to happen. And if you know who this person is, police in Philadelphia want to hear from you.
Update: A man named Carlos Figuroa Fagot (golleeeee, what a name!) turned himself in today. His family stated that he was very surprised that his actions were recorded on video and that he was horrified and scared when police went ahead and aired it. That's one dangerous creep off the streets for now.