For films and the like it might be easy to get around this - the release teams could sign their releases. It might be theoretically difficult for them to get their public keys out into the ecosystem, but it would be pretty easy in practical terms.
For arbitrary data you could possibly have a rating/tagging system. I guess the content industries could fudge the votes, but if the votes were tied to identity/pseudonyms they'd have to be clever to beat any kind of data analysis.
The effectiveness would probably depend on how many garbage alternatives you provided, and how sophisticated/varied their uploading is. Too many bad files and voting and signing might not be practicable, and you'd have to resort to some kind of automated spam-detection. White-listed sources are workable in the worst case, but I'm sure there would be other, better ideas around.
For arbitrary data you could possibly have a rating/tagging system. I guess the content industries could fudge the votes, but if the votes were tied to identity/pseudonyms they'd have to be clever to beat any kind of data analysis.
The effectiveness would probably depend on how many garbage alternatives you provided, and how sophisticated/varied their uploading is. Too many bad files and voting and signing might not be practicable, and you'd have to resort to some kind of automated spam-detection. White-listed sources are workable in the worst case, but I'm sure there would be other, better ideas around.