I played paintball in Australia and I just had to sign a normal waiver about them not being responsible for injuries

Ownership of paintball guns is regulated under the state-level firearms act in most (all?) states and territories.

You can use them under the direct supervision of the licensed owner, but it's still quite restrictive. If you were to take one and shoot at cameras on the street it would vandalism plus firearms offences, most of which start at inversion of innocence, massive fines and move pretty quickly into prison time.