i think it's our human reaction is, here are a group of men, not women, but a group of men and they're not doing anything. >> but what would you do confronted with an out-of-control thug mercilessly beating someone right in front of your eyes? would you call the cops? tell him to stop or look at the wall as if it wasn't happening? >> if one person would have stood up, one person crosses that line, one person would have stood up, i think, you know, things could have turned out a bit different. >>> coming up, a horrifying hit-and-run leaves a 78-year-old man paralyzed and waiting for someone to help him. >> he was bleeding on the back of the head. he was bleeding through his eyes. through his mouth. all over the place. >>> and later, what would you do if everyone around you suddenly froze in place.