Some background: a little while ago I built a library called "Checkboxland" at the Recurse Center for rendering stuff into a checkbox grid. I recently made an update that lets it render arbitrary images and video. The video feature supports HTML MediaStream, which is what powers the webcam demo.
This is really fun! I'm not sure of the practicality (particularly with the QR demo, my boxes don't turn bright blue like yours apparently do, so its pretty invisible to a scanner) but if it looks cool then that's reason enough in itself
You hint in the docs that you make some efforts to render efficiently. Are there any write-ups on the optimizations or it is just as simple as updating only when needed?
Agreed, just trying to keep the tutorial simple for now. My other web-animation/education project (https://sparkbox.github.io/bouncy-ball) uses requestAnimationFrame more heavily.
Now that I think of it, it might be worth adding an asterisk and footnote about requestAnimationFrame to the post.
My coworker hacked together a demo that's pretty wild: https://twitter.com/nathanAlan/status/1436145205019922440