MG,
I had read somewhere that in some circumstances, the gopro images or video can be shaky due to too much light. This forces the shutter speed way up which shows up as a wobbly image (remember, no mechanical shutter, it records pixel by pixel, line by line) or jumpy video. Conversely, if theres not enough light, the shutter speed is slower, thus inducing blur.
I can go into more detail if you want, but id rather not type that all up on my phone, nor while im trying to fall asleep lol. (Photography is my living)