This is called train dodging. Apparently, doing cartwheels or backflips doesn't cut it for the kids anymore. According to Russia English:

"This is needed to be done fast, because if one is appearing before the train too long before and machinist could see him and start breaking, so they run on the rails just before the train so he couldn’t start breaking and fell down on the rails, then the train moves above the person at his maximum speed, just a few inches from his head and back."

Here's another video filmed by a Dutch kid. Here's another one by a bunch of Russian kids. Of course, there's a good reason not to try this: you might trip and die.