If I may, a well-meant cautionary note...
Any hard object mounted to a helmet will increase the risk of helmet fracture or penetration in event of an accident, so be cautious in use, please. It would make for some spectacular video if the worst should happen, however!
I have noticed some of the GoPro camera videos that use a chest mount seem to have a steadier presentation and are easier to watch than helmet-mounted cameras that (naturally) tend to pan whenever one turns their head. I think I like the chest-mount videos better for that reason.
Just another data point or two to consider...
Best,
Dan.