Here is an interesting addendum to last week’s story about Mega, the new file storage service from Kim Dotcom of MegaUpload fame.

Recall that Mega encrypts files that users store on its servers, with keys that only the users know… unless they publish URLs that contain the keys, like this one.  This means that Mega can’t know whether or not files on its servers are infringing, unless a user publishes a URL like that.

As TorrentFreak has found, Mega is crawling the web in search of public URLs that contain Mega encryption keys.  When it finds one, it proactively removes the content from its server — at least if the file in question contains audio or video content — and it sends the user who uploaded the file a message saying that it has taken down the file due to receipt of a takedown notice from the copyright owner.

It’s impossible to say for sure whether this is a blanket policy, and of course Mega’s web-crawling technology probably doesn’t work perfectly.  But if this is Mega’s policy, then Mega is being at least as aggressive as RapidShare in going after public links to infringing content.  RapidShare finds public links to files on its service and, apparently, examines them with content identification technology to see if they are infringing.  According to TorrentFreak’s findings, Mega does no analysis; it uses no fingerprinting or other content identification technology; it just takes the content down.  It has taken down unambiguously legal content.  (My file wasn’t taken down, because it’s just a PDF of a presentation that I created, and/or because it’s only on this blog and not on a known P2P index site.)

Mega could be doing this in order to conform to the terms of Kim Dotcom’s arrest.  Whatever the reason, it helps make sure that pirated material on Mega can only be shared by sending encryption keys through means such as email… or perhaps URLs  that are publicly available but are themselves encrypted.  And if you truly want to share audio or video material to which you have the rights, then Mega wasn’t going to be the best place for you anyway.

A commenter on TechDirt put it best: “So we’re still allowed to share the stuff, but just not on linking sites? Seems fair enough to me. Probably for the best too, since some dumbasses clearly don’t know how to hide their copyrighted material properly.”