Rather than just being a fun little project, I could see there being a few practical uses for this: If you could modify the protocol so that the 'QR code' could dynamicly resize down to be in the worst case 1 pixel for the whole screen, you could potentially do line of sight communication using just laptops between tens of kilometers away[1]. There aren't a lot of situations where you'd need that, but I could see scientists on a remote research mission finding in handy to be able to just pull out their laptops and send messages between mountain tops by just double-clicking some kind of application.
A crappy webcam that could do 10 frames per second that was looking for an entire monitor in the on/off state could send O(10) bits per second which would be useful enough to send small text messages. If you used a telescope, you could actually send real amounts of data.
[1] https://www.technologyreview.com/s/539826/how-far-can-the-hu...
Edit: Upon close inspection of the article I linked, it says later in the article that you could only see the flame 2.76 km away, but I don't think that changes my point very much since a laptop screen would be brighter.