I found someone with exactly the same problem as me, but unfortunately the answer (read the manual) wasn't helpful as the manual doesn't explain how to turn this function off - only how to turn it on.
I finally figured it out for myself (but it did take months of trying), so here's the answer for anyone who's having the same issue.
- Just turn your camera on and make sure it's in video mode.
- Now turn the control dial (the wheel you'd use to scroll through your photos) and you'll see different video options appear - just select the plain video camera image.
- You're done.