Something like VLC.js is anything but "[a] [s]imple [r]equest" :)
The web experiences some kind of rot anyway. As long as you can still access and play stuff you really want in at least one way (VLC), is the instantaneous part such a win?
It's a technical solution to a problem most people don't face. Are people really facing that many multi-media files that can't be played? Two bigger issues that come to mind: 1) stuff hosted on closed, proprietary sites that then close down 2) how to find stuff (especially with esoteric or unusual content). So IMO, VLC.js probably wouldn't "fundamentally change our relationship to a mass of materials and files out there".
I agree there is a delivery issue, but again I think it's findability and hosting - hence why youtube/soundcloud/spotify/netflix is a thing.