If you'd try to pull off stunts like ones presented on that video, you'd smash your phone into million pieces in the first 30 seconds. Twice I almost dropped my phone while playing Ingress, and that game doesn't make you run or react to events instantly.

I was thinking the same thing. I would run into a wall or a car as I fight someone. I can see the game being successful at someone's house with a decent size property. However, why not just grab a paintball gun instead?

When playing hvz, stumbling was pretty common. Out of 40 players, one or two would get scraped up on the concrete per game. Running into walls, poles, and trees pretty much never happened.

The streets were very strictly off limits. And if there was a car (like a Public Safety vehicle) patrolling the campus sidewalks, all play stopped until the car was a certain distance away. No running, tagging, or shooting on the streets or by a moving car (parking lots were okay IFF there were no moving vehicles). Anybody in violation was immediately thrown from the game and banned from the next.

Safety under these conditions was not ever a problem. A sprained ankle was the worst injury we ever had, and that's going to happen in all sports.

There is also the possibility of dropping your phone...

At the beginning, it looked like the girl had a strap that went from her jacket to the phone [1], but I only caught it at the beginning of the video.

[1] http://i.imgur.com/UmeQN48.png