My idea is that a meta-database dedicated to storing information about files should be the basis for user-submitted content.
This information would include include comments (stored and editable by the commenting user), and the file’s URI.
The comments could be made in a new standard format to give an impression of how they should be interpreted.
The interpreter program (not necessarily affiliated with the meta-database) would make comments user-readable, and allow easy commenting.
YouTube example:
Person A wants to post a video file.
The interpreter asks them: for the file’s location on their hard disk; for a description of the file; if it’s ok to use the computer’s video processing software to make lower-quality versions.
Then the interpreter makes the file public. It submits the URI to the meta-database, along with a comment including the description and lower-quality URIs.
Someone using the interpreter could go to the file’s URI, and the interpreter would show a webpage displaying the video and relavent information from the meta-database.
The interpreter would recognise that the first comment contains a tag, and was uploaded by the same MPID as the file, and would therefore display the contents of the tag as that of a YouTube description. This recognition would also enable YouTube-ifying existing videos.
The interpreter would recognise that the first comment also uses a tag to store the lower-quality versions, and would include them in the HTML5 player (I don’t know if this is how HTML5 works).
The other comments would be displayed as comments, preferably in a Reddit-like layout. Not sure how upvoting/downvoting would work.
Executable file example:
A site offers a download of an executable file.
Someone sees that this file is dangerous, and comments a summary of this in the meta-database.
Another user downloading the file (via a comment interpreter) would see this warning as they download the file.
Spotify example:
Like the YouTube one without video.
This could be linked to files describing the albums and artists to allow better categorisation.
An opt-in user-tracking system could be used to determine related sound files to provide suggested tracks.
Meta meta example:
Someone finds the URI of a user comment, and then comments on it.
(I’m not a programmer)