wow.. from what I can interpret (via Altavista), it seems that purse snatching, robbery, pickpockets are rampant in China. These 2 got caught and paid the price from citizens that were fed up. The police were not there and these guys paid the price... the stones were a bit much..
I have witnessed a beating before but not in China, in TO, an street person was beaten for spitting on some guy's car.. that was brutal too, kicked, punched, dragged and spat on and this was only 8-9 years ago in the club district, try fighting there now and see how fast you get stabbed or shot. Heck you'll get shot for looking at someone the wrong way, or stepping on their shoes inside the club.
From my travels in China this is probably in one of the smaller cities, the people are less educated and police are no where in sight. There are gangs of street thugs who prey on the weak, usually their bark is worse than their bite. Purse snatching is rampant done by drive by scooter. They rarely rob you with a weapon, that would probably explain why they just lay and took the beating.