The full extent of the crack is just out of shot, but one of the branches of it can be seen under certain light up in the top left corner, the angle of the crack is just in line with the angle the camera looks at it, so it's only when light passes directly through it that you can notice it.
If I switched back to 720p you'd be able to see the whole crack. I think I'm going to have to buy a proper 3mm lens cover for it and tape it over the front of the whole camera or something.
The lens kits for the Contour ROAM series weren't shipped outside the US, all the lens kits online were for the Contour HD, which takes completely different lenses which don't even come close to fitting. So they're a massive bugger to get hold of. I emailed Contour directly and they sent me one lone cover as a "good will gesture" but they wouldn't let me buy a set or anything.
So if you get one, definitely get a cover for it immediately.