haha.
Well, basically you are looking at a transparent 2m ball with lasers at the core. The ball was also inflated with mix of smoke and air so you see the laser traveling through the smoke inside very clearly but then disappears outside until it hits the wall. Still missing more lasers though.

The lasers re not that strong, also they will shut down if the ball stops moving. This minimizes the exposure to the lasers.

This was my first thought too (how do you protect the crowd?) I imagine you could also do some crazy things with a gyroscope inside and PWM on the lasers, so that the lasers facing the crowd are weaker. Plus some sort of elevation sensing that determines how bright it is overall.

It looks like the ball is blocking the exit of the lasers -- it'd be really cool if that wasn't the case.

They are not cheap