I use a rubber strip mount like the video above. I made a few different sizes until I found the dimensions that work best on my bike. The flashlight does move it's aim sometimes when I hit a bump, but it's easy to wiggle it back to the correct direction.

I first tried using the flashlight as a helmet light. It was very nice to be able to point it into a turn. But I didn't like having to keep my head steady so the light wouldn't drift all over. Now I always mount it on the bars.