You also only really need the video to push the browser to do things in HDR. You can’t express a CSS colour way outside the normal range, but blending calculations are not clamped so can be used to get the colour. https://github.com/kiding/wanna-see-a-whiter-white was posted here a while ago and demonstrated the technique.
I'm not sure why you're being downvoted when that's exactly what's happening. The QR code comes from the mask-image in the inline-style, not the video.