[Bug] wrong projection on 360 videos

[iBicha]

Describe the bug
Currently 360 videos (webgl) are not properly projected (see screenshot)

Steps to Reproduce
Open video sPyAQQklc1s

Screenshots

Additional context
It's known that YouTube moved away from Equilateral Cubemap a while back (which what causes the wrong projection in the screenshot) to using the Equi-Angular Cubemap (I hope these are the right names)

Some people figured out that changing the user agent can get them the old format back ytdl-org/youtube-dl#15267
Also related videojs/videojs-vr#179

But "Equi-Angular Cubemap" does not necessarily have to be projected as described here, even projecting to a cube with the right UVs can be a huge improvement compared to current state.

As an example of that, you can test this html file (zip because github won't let me html)
webgl-viewer.html.zip

[iBicha]

Relates to #2394