http://www.youtube.com/user/swedeis
That was made with a cheap Aiptek mini-camcorder that I bought on a lark at Target. It records to Compact flash memory cards. I added a wide angle lens to it and it helped quite a bit. A proper microphone is next on the list of "mods"
Since it is so light it isn't as likely to break off the mount and kill me. It also doesn't move as much. The mounting system needed is so much lighter and easier to manage. I used an old bicycle cargo bar clamped to the headrest with a cheap tripod head mounted to the end of it. They are cheap enough and small enough to use multiple on one vehicle to record you, the footwell, the engine bay, behind you and even pointed at the wheels.
The trick with these is tricking the display interlock switch (cuts power when the flipout LCD view finder is closed) and providing a central button to start/stop the recording. Pretty simple. One DPST switch for power and one SPMT switch for start stop recording. Use a quick-release connector to make installation and removal easy. Since these mini-camcorders are marketed as a webcam as well, they could simply be connected to a USB hub and a laptop or built-in Mini-ITX computer could potentially record from them all at once (though I've not tried it so I don't know whether a laptop would have enough performance to do that successfully).
The newer models aren't much larger than my DV3100+ but some can record in native HD format, most use faster memory modules with more storage capacity but can still be used as webcams, etc. Aiptek isn't the only one marketing products like this. Check out Amazon.com for other companies offering memory-based camcorder devices.
The issue with using regular hard drives in a vehicle (ask your local police man about laptop drive failures) is that they don't live long when under constantly changing g-loads. The internal moving parts don't take kindly to sudden changes (think of an old record player with the needle replaced with a high-tech maglev version. Now replicate that 4-8 times within a tiny container the size of a stack of cards, now start shaking it around.) Not to say it won't work, just be prepared to back up the data often and carry a pre-configured spare drive just in case you have a failure while under way. CD/DVD based drives can have similar problems, though the discs rarely are damaged, just the data doesn't burn as well or not at all (try to write your name with a laser pointer while someone keeps bumping into you)
Either way, make sure you plan to use a better mic to get decent sound (whether you record separately or using the camcorder, is up to you) the built-in mics are not directional and will pick up the loudest noise nearby (usually you bouncing around in the seat, the strap you forgot to take off, etc) You'll also want a wide angle lens of some sort. Sun seems to be a common brand for more or less universal lens solutions, Sony and others have direct fit versions for some of their models.
Enjoy!
Stefan
