Yep. Done it several times. Also have hit the camera switch option and see my face on my screen. This usually scares me back to reality.
Sure but if I want to take a picture I make sure it's on camera, if I want to make a video I make sure it's on video. I don't really see why it's that difficult. As far as accidentally switching it in the process of doing my thing... sure I may have done that but didn't put much thought into it and changed it back. I certainly didn't worry enough about it to warrant a thread on a forum.
My point is if you can't look at the little selector and see it's on video then you have bigger issues in life than issues with your iPhone. It's not rocket science people.
Never made a mistake in your life?