Offer a built-in hidden dash-mounted camera to record accidents.
Very few car makers offer a dashcam. The Corvette offers a 720p dashcam as a $1795 option on the base car.
Always-on dashcams are useful to identify vandalism while parked.
A good third-party HD dashcam (single direction) costs about $100-200 and a two-channel (front and back) dashcam for about $350, plus installation.
Update: The front AP1 autopilot camera is not usable as a dashcam. It is only connected to the autopilot hardware and does not connect to the main CPU. It is fairly low resolution, has a narrow field of view, is monochrome/red, and uses a non-standard 36 fps rate.
Update 2: The AP2 camera set is better situated to be used as a dashcam. All but the rear camera are medium resolution, but they do use a monochrome/red pixel arrangement for higher sensitivity. With enough processor power (an unknown) the images could be processed into a cyan/red sort of duotone image.
Most of the available flash memory is used for maps and caching, so with the current design, even if can record there may only be room for a limited amount of recording. Perhaps Tesla can record to a customer-supplied USB flash drive, although the bandwidth may not be high enough for a full 8 camera recording.
Implemented in V9 software in October 2018. It can record front, sides, and rear in full color while driving and parked (for HW2.5 cars only, made in August 2017 or later). Older HW2.0 cars can be retrofitted with AP 3.0 hardware and MCU2 and get the full dashcam features.
(voting combined from a close duplicate that has been removed)
The Tesla already has a rear HD camera and Auto Pilot uses a front camera as well.
Even if, as Manchu76 said, the front camera is dedicated to the Auto Pilot and can't be recorded, HD cameras are fairly small these days, couldn't another one be added to the same enclosure? Or make the enclosure a little bigger, it's not like it's in the way...
Streaming video over a phone network would be pretty slow, we'd be better off recording to SD card, and uploading over Wi-Fi when we get back home. Having a microSD card slot hidden in the glove box (or elsewhere) would mean even if the car couldn't be driven after the accident the card could be removed so you can take the footage to show your insurer/the police.
This could give you front and rear footage (though the rear camera probably gets dirty all the time - the one on my Lexus does), if it's on a overwrite loop connected the the car's crash sensors (like what deploys the airbags) it would require no input from the owner/driver. Options could be included on the display to control how long it records for before overwriting, and also an option to manually stop the overwriting (in case you are following a car that is in an accident, for example, and want to keep the footage).
And maybe, just maybe, it might bring the cost of insurance down slightly...? We can live in hope.
Dash-cams are more and more common and being used especially to prove that one is not responsible for an incident. There are several posts on forums about installing them on the Model S and it's obviously non-trivial, especially as there is no obvious place from which to get power - there is only 1 12v socket, which you might need for a phone and, anyway, it's in the wrong place to power a camera.
Since the car already has front and rear cameras - even if they are at the moment doing other jobs - it really does seem obvious to make them able to record. Recordings could be saved in a Cloud or on a USB stick, perhaps. You'd need some software that let you play the files, including their GPS (position and speed) and G-force information.
The front camera is a 'Dedicated' camera. The scope of it's focus, is to read road lines, signs, ect. It is merely looking at a pixel count per square area, so as to compare what it sees to a known object. A.I.
This does seem like such a no-brainer - especially so given that all the camera hardware is already fitted. I think a separate unit for actually doing the recording would be preferable than relying on the car existing hardware. I would think it not difficult to 'borrow' the car's cameras for this purpose.