I have one of these.

Don't try to use it with your helmet. If you are paying attention to traffic, your head is on a swivel making for some rather fast panning video, enough to get viewers motion-sick when reviewing it on the TV or PC.

I mounted mine next to the headstock, because there's less motion there, even when compared to a handlebar mount.

The audio is crappy on it, but at least you can use it in bad weather, which is probably why the audio is bad--waterproof down to 3 meters.