1. Pick a video
Every code holds exactly 53,698 bytes — the same fixed budget the shipped scanner already knows how to read. Shorter clips come out sharper; the whole thing gets squeezed to fit, however long it is.
If your browser supports it, the code is automatically signed — a small trailer (108 of those bytes) proves the content hasn't changed since you made it, and names it with a short address. Your signing key stays on this device (localStorage); nothing is uploaded anywhere.
2. Your code
3. Print it
Print at 100% / actual size (not "fit to page") for the physical size below to hold.