What's opaque or bad about a media library? They only exist because the filesystem is inadequate for cataloging and interfacing with the complex metadata associated with media files.
I don't have my "media libraries" from 20 years ago.
As soon as a tool tries to move my files into an internal representatation I cannot control, I delete the tool.
I highly doubt the music file metadata shown in the video only exists in an opaque internal representation within VLC.
I think a tool should embrace the filesystem as much as possible. If metadata doesn't fit in the fs view, then perhaps store them in hidden files next to the actual files. Needless to say, if these files are not there, the system should deal with that gracefully.
Sure, or in tags within the files like almost every music player, but that doesn't preclude there being a media library which is more like an interface to/cache of that metadata.
If your goal is simply to play a video file, it's sheer overhead.
I don't want every text file I download to be categorized and moved into a semi-permanent collection. Nor do I want the same as a default for image files, music, video, or anything else. Some things are ephemeral.
It already is and it is called desktop search.