Both products have excellent reputations in the professional cinematography and broadcasting listservs that I frequent. I like the Contour a bit better as it uses LEDs as an orientation guide; neither camera has a viewfinder.
If you're looking for a video camera as an occasional "helmetcam" then I love the Flip Mino HD.
I own a Panasonic DMC-TS2. Waterproof, crush proof and for a full auto point-n-shoot, with a little adjustment to the exposure index, it actually takes decent photos as well as better-than-it-has-every-right-to-be 720p AVC-Lite video. That camera would be light enough to mount on your helmet occasionally.
The way low-quality cameras record video is by writing the frame from the top to bottom. When you turn the camera, the top row gets the current frame, while the bottom row is still being written with the previous frame. This is known as rolling shutter.
This video shows footage from two cameras, side by side, to demonstrate the effect of rolling shutter.
The camera you linked to will result in the video footage on the right, under 3 CMOS.