Legalities or not, what was done by this pilot was foolish at very best. My brother, who flew Sikorsky S-58 choppers told me that flying low around camps (he water bombed fires mostly in Northern Saskatchewan) was always a great risk because of the possibility of flying debris. Tarps were especially a problem as at low altitudes, a ring vortex is established that causes debris to get thrown into the air that then rotates up and then back in toward the main rotor. You can actually see that starting to occur in this video. They're just really, REALLY fortunate that one of those tents/covers didn't fly up like some of the other debris actually did. Those tents and covers in this crowd are great tarps. They say there are few old helicopter pilots. My brother is one of them for good reason. I'm thinking of sending him this video to see what a safe, old pilot might comment on that stupidity.