GoPro as a Dash Cam Attached to Headrest

The need arose at some point when I needed a dash cam to do some work. For some reason, I couldn't find a local store with the GoPro Hero2 vehicle package with the suction cup mount at the time. It was either the helmet mount or something that was worse -- I forget what.

GoPro Hero2 Camera

Headrest Mounting a GoPro Camera
Long story short, I realized that the passenger seat headrest is about the same size as a head or helmet. Why not attach the camera to the headrest then?

Aside from not being able to use the passenger seat without bumping one's head or blocking the camera, it appears there's a very good reason: unstable platform. I avoided looking up GoPro videos on YouTube for the longest time. When I did, I noticed that people were able to take very smooth footage using, I believe, the GoPro vehicle suction cup mount.

Over a few hours of footage were taken with the headrest method. At least I saved $35, which I eventually spent?