some of the videos are also unbelievably sinister, like the one coming up. it shows a brutal attack on a complete stranger by a man with a hammer. the only thing more shocking than this brutal attack caught on surveillance camera is how random it turns out to be. >> actually seeing that tape was just -- it was horrifying. yeah. and yes, his intentions was to kill, you know, someone, but it just happened to be my son. >> it's about 12:15 in the morning when 20-year-old duane taylor, a lab technician from the university of pennsylvania, boards the broad septa train line in philadelphia to head home after a day's work. he dozes off listening to his ipod as the train heads north. next to him, a man is standing with his son. the little boy is told to sit down. then for no apparent reason, the