I understand mounting tight so it don't go anywhere hopefully, and to keep the camera from bouncing all over when travelling and making the video jittery, but one must also keep in mind, the shock going INTO the camera. IF it's say just bolted to the frame, every bump you hit, there is no buffering, that jarring is heading right into the camera, eventually that is going to stress wear stuff out. Break stuff internally and externally. Some sort of rubber buffer, like between the mount and frame will keep it tight but will give you worlds better support longevity over time.
I ran into this problem on my boat with my GPS / Sonar's, the bang bang and vibration on the waves would just tear up the plastic, AND the metal too, any 90 corners on that cheap shitty bracket? I can pretty much guarantee they did not heat stress relieve that thing, they just stamped them out and it will break over time too. A bike would be no different shock wise.
Finally, and I am pretty sure you know this but if you are tethering, make sure the tether is short enough / positioned in a place that if it ever WERE to let loose, that caught on the tether swinging camera does not swing it's way into say your chain sprocket or somewhere it could cause a hazard to you.
Aaron