To record video to the rear, the lens housing must be rotated so that the lens is facing rearward.  Grab the lens housing and twist.

After rotating the lens housing the video will be upside-down (because the lens is now upside-down).  To flip the video:

1. If your unit is currently recording video, press the REC button to stop the recording.

2. Press the MENU button 2 times.  The wrench icon at the top of the display should be highlighted.

3. Scroll down to “Rotate” and press the orange button.

4. Highlight “On” and press the orange button.