Yes to what everyone said. FYI, those were dive lights they had on their helmets. I have to go retie my bungie for the right light on my helmet this morning. I'm using backup lights on the sides of my helmet, but they were using primaries. In cave diving, primaries have canister batteries that are attached to your dive harness. Usually they have a Goodman handle that you slip your hand in and the light rides above it. That gives you full motion with your fingies, and your light. It's better, generally to not have your light on your helmet cuz of the backscatter. But when surveying, or some other activities, you need to use both hands and have the light point at your hands, so it doesn't work to have the light on the back of your hands.
One of my lights uses a soft Goodman that has a plastic bracket that then has an elastic strap that goes around my hand. One of my buddies took the same plastic bracket and bolted it to the side of his helmet, and he mounts his primary there.