Maybe I missed it in the instructions, but how does the system handle the shutdowns? Does he manually shut it off each time, before USB power is turned off, or does it just handle the power cut-off gracefully? I worry that the file system will get corrupted after a while.

There was some discussion about this on a pi board a while back; it seems that the only safe way to handle power-off is to (1) have a battery on the pi, and (2) catch the USB power-off signal and then shutdown gracefully.

At least, that's how the Chinese dash cams seem to work. They all have rudimentary batteries that last about one minute unplugged from the power outlet.