Always seems to be Russians who do these crazy things. Parkour can be fun and challenging eight feet off the ground and less fatal if it goes wrong, but the high adrenaline seems to demand it be a life or death thing. I guess that's why the Russians invented their fatal version of 'roulette'...
Parkour is an activity people choose to participate in of their own free will. It is not a professional sport. Adding regulations to it will not prevent injuries or death. Outside of prohibiting it in public and private places, it could be unconstitutional to implement restrictions or regulation on Parkour.
Parkour is basically free-running, so it's learning to move, jump, climb and flip on, off and through terrain. That includes cities, the outdoors, railings etc. There's not really a way to make it safer, except to make sure you can't do it unless you've trained for it. Even then, there's risk in climbing, jumping off a building etc. It's a risky sport.
People are going to make poor choices that result in them getting hurt or killed. The government cannot regulate away every bad choice that people can possibly make. Instead, people need to have the good judgment for themselves not to take risks. People need to think for themselves, and not rely on the government, even when they are just young people.