Sometimes, "Help" Is Implied ... Not Spoken

I saw a episode of ABC's 20/20 that disturbed me some. The crew of the show set out to place actors in the park and have them fake an argument. Next, the crew placed cameras and microphones around the area to record if there was any public intervention. This "fake fight" was on the verge of becoming physical, and yet most people walked by as if nothing was wrong. I am a firm believer of minding my own business, but when a man clearly has a physical and/or psychological advantage and is starting to shove the woman, I would think it's time to break it up and have each party move on. What was more amazing is that when the situation was reversed, nobody stopped to help the guy when he was being abused. Interesting. Have we all become that cold toward one another? What if the next time you saw them was in the obituary?