Current marker image is set. Replace it
Replacing it recompiles tracking — the QR code and link stay the same, but the printed/physical image needs to be updated to match.

Leave blank to use a generic default. This is what tells first-time users what to do — many scan the QR, land on a blank camera view, and don't realize they need to point it at something specific.

Browsers block autoplaying sound until someone interacts with the page — this trades one upfront tap for video/audio playing with sound automatically afterward, instead of visitors needing to find and tap a separate mute button. Off by default; some experiences read better starting immediately.