OK, there is basically no user interface for the dash cam. Here is what I've figured out:

1. If you stick a USB key in one of the front USBs and one of the partitions has the folder TeslaCam and it is formatted as FAT32, you will get a Dashcam icon.
2. If the icon has an X on it, it means it found the USB but something is wrong. The only fix appears to be to reformat the drive.
3. Do not just pull the drive out to look at the videos, you have to long press on the icon
4. It looks like if things are working properly, you get a camera icon with a "RED" button on it indicating recording. This seems to create an hour circular buffer of files named REC
5. If you tap on the icon, you get what looks look likes a download GREEN button, this saves the last 10 minutes into another set of files called SAV
6. Theoretically if you create two partitions, you should be able to have one that is the Dashcam and the other which is USB music, but when I tried this, I immediately the the X icon and had to reformat.