Add attribution or delete CERN video

[kainino0x]

We have this test 360 video file of LHC at CERN:
https://github.com/webgpu/webgpu-samples/blob/main/public/assets/video/pano.webm
Added here: #52

It's nice because it's small, but we need to put a proper attribution on it, discussed here:
#525 (comment)
(Right now it links to foo.com)

I finally found the source of this video file https://github.com/mrdoob/three.js/blob/6f2ec7584e5a6463bf5f99b1a521f16cad432d65/examples/textures/pano.webm
But it doesn't specify a license either. CERN's license is here but we don't even know if it's published by CERN.

I think we can just remove it, since we now have another properly attributed 360 video.