Review on The Ultimate GoPro Mouth Mount: Capture Epic Adventures with Ease! by Jerry Forehand

Great for video, that's how it is. You have to hold it firmly with your mouth when you're moving and want smooth footage. Cons: Unless your mouth looks 100% like an iron clamp on a mouthpiece (which is harder than it looks), it moves easily and your teeth get chafed by saliva dripping onto the gum in your mouth, causing it annoying squeaking noise that is captured by the camera. So if you want to use the original sound of your video, those annoying noises will be everywhere. My solution was to cut a small rag and place it on the mouthpiece so my teeth were on the cloth and not the rubber and I eliminated the grating noise. You could build something like this right into the mouthpiece.