This isn't about video, it's about 3D apps. The top 3D porn apps need power similar to the top AAA video games to simulate hair, physics, and to render realistic looking characters. In the same way AAA videos games don't run well in the browser., VR apps in the browser are just as bad.
Also note: even if we're just talking video Safari does not support a webpage going fullscreen which is arguably required to do VR video. But just to be clear again, this isn't about videos, it's about high end real time 3D porn
