XR stage
The thing the model element can't do: two different videos, on two pieces of geometry, at the same time — one wrapped around the sphere, one on the cube. Rendered with WebXR + three.js video textures instead of USDZ docking.
WebXR immersive mode is not available in this browser — the inline 3D preview above still plays both videos.
Experience
Why this works here and not with docking
WebXR gives the page its own renderer, so videos are ordinary GPU textures: any count, any mesh, any UV mapping — the sphere is genuinely wrapped. The trade is losing RealityKit's rendering, the system video player, and docking integration (WebKit/explainers#136 asks for that gap to be closed from the other side).