If you watch the video you won’t get what’s cool until about halfway through. The art itself is pretty Bansky-esque (not that there’s anything wrong with that) but the way the artists have decided to extend their work is the hook.
The idea is that each place they leave their graffiti they also leave a little plaque with a code. The first person to text in the code gets a copy of the work for free. The next person pays $1, and it continues to go up.
It’s art. It’s a game. It’s genius.