I cannot count how many times friends have called me to ask "So, how do I sell my used car?" I never have a good answer (The trade-in-to-dealer process is the easiest but by far the worst financially) .
On the question (from the video) of 'What if it gets stolen?'
"At worst, you get paid for the car."
Heh. This brings up a number of thoughts -- I mean, in the end, your goal as a seller is to sell the car. If it gets stolen, your insurance company pays you for the car, so...mission accomplished?
If that becomes a regular occurrence, it creates a weird market condition -- thieves win because they get an easily-stolen car. The seller wins because he's sold his car quickly. So the insurance company loses -- and who gets left holding the bag?
(Not saying this is a real risk - I think these guys are going to do wonderfully - but a thought experiment...)