This is oversimplifying a very complex question. It's not easy to give a simple answer.
The Contour, eg, is a very specialized kind of camera: a mount or helmet camera with a fixed very wide angle lens, most useful for getting subjective action shots. It would be great for underwater with the proper UW case. A camera that's similar to the Contour is the GoPro HD Hero2. You can see a lot of comparisons between various Contour and the GoPro models on the web.
If you want to get a tight shot of anything even slightly distant, though, neither is going to be a useful camera, and their wide angle lenses introduce a kind of distortion that will produce pretty ugly close-ups of people as well. So you might instead (or in addition) want a camcorder with a built in zoom.
I'm assuming, btw, that this earlier post [webmasterworld.com
...] from April 2010 describes some of your requirements. One big change from when you posted... most new cameras are using solid state memory chips, and hard drives are essentially phased out.
I think you need to decide what kind of subject matter you're going to shoot, and also decide on how really serious you want to get about the videos you make. It helps to have a sense of photography, writing for video, and editing as you begin.
- If you're going to take the camera on extended trips, you will want replaceable batteries and swappable memory cards. A long enough trip might require a solar charger.
- If you're fussy about exposure, you're going to want a camera that gives you a degree of manual control.
- If you're going to be shooting people who talk, sound quality becomes a very important factor, and you'll want some kind of external microphone input. You'll then start quibbling over how dependable the microphone connectors are, and how heavy they are.
- Weight, reliability, lens quality, image quality, degree and quality of image compression, also are considerations. A camera that's too light weight, btw, is extremely difficult to hand-hold steadily.
DSLRs can also provide some extremely good video, but you run into some tradeoffs - technical and ergonomic limitations - when you use them; and to focus them in video mode you may need to find some old manual
SLR lenses. DSLRs are not optimized for video, but, in the right hands, they can be amazing video tools.
I've also seen sort-of-OK video from iPhones and iPads, albeit the microphone is on the wrong side of these devices for recording good sound. Ultimately, budget also enters into it. No way to give a complete guide in one post. Post follow up questions as you think them through.