The Muvi's utterly s**t, horrible image tearing- the gadget show review has some footage they did themselves and it's just worthless, even at walking pace.
I'd say get a Go Pro too, sure they look goofy but they're very, very good. You can mount them anywhere, because of the tiny size and versatile mounts.
The Contour HD has higher quality but it's not so easy to mount, you're more restricted in where you put it because of the size and shape. And their customer service has been absolutely awful in the past, they launched the first vholdr long before it was ready then didn't support it when it turned out that the initial run were pretty hopeless.