How can I switch Video off and camera on?

To stop recording, tap the red button.

As far as switching modes, It depends on which iOS you are running. First try swiping up or down on the screen until the selected mode that you want to use appears in yellow text. You can swipe anywhere on the camera screen to do this.

If running iOS 8, just touch the mode that you want to use or swipe or scroll with your finger until it appears and then tap it.