I received V9 last night and have been playing with the dashcam today. I have a couple of observations that I thought I would share which will hopefully be useful to others in the future.
I have a ton of spare USB sticks lying around, so I grabbed a 4GB stick, formatted it FAT32, created the TeslaCam folder, and popped it in my car. Within a few seconds, the camera icon with the red dot showed up. SUPER SIMPLE!
I decided to take it for a test run, so I went on an errand to the grocery store and came home. The total driving time was less than 30 minutes. I'm in IT, so I'm kind of anxious/paranoid about pulling out a USB stick while it is being written to, so I pressed-and-held the icon on the screen and the red dot went away, indicating recording was paused/stopped. I pulled out the stick and went inside to check it out.
What I found was that the only thing that was saved was the last drive (in other words, the trip from the grocery store to the house). The trip from my house to the grocery store was not there (despite being about a 7-minute drive there and 7 minutes back). So, keep that in mind. I'm guessing as soon as you park, get out, and lock the car, that the next time you get in, a new "loop" starts. So if you want to save anything from your drive (and you didn't tap to save a clip), you need to do it before your next drive.
The way it seems to work is that it saves video in 1-minute increments (my guess is that it buffers for a minute, then saves it to a file, buffers, saves, etc). Something that disappointed me is that the final minute of my drive home was corrupted. Every other file worked fine, but the last file would not play, despite me stopping the recording before pulling the drive. I imagine yanking it without stopping it is even worse. So, that's something else to keep in mind. If you want to make absolutely sure to have that last minute of recording, I'd do a manual save (tap the icon on the touchscreen) before pulling out the drive.
Last quirk - when I was done viewing files, I took the drive back to my car and plugged it in, and the screen showed the camera icon but it had an X where the red dot is supposed to be. I pulled the drive and tried the other USB port, same result. I rebooted the car, same result. No matter what I tried, I couldn't get it to resume recording. I took the drive back to my computer, reformatted it, recreated it the TeslaCam folder, and took it back to my car, and it almost immediately started recording again (red dot). It's possible I could have just deleted the data instead of completely reformatting it, but whatever the case, wiping it and restarting it seems to have resolved it. I don't know if this was a quirk or just the way it works for now.
Hope this helps!