A more nuanced version of the system newhouseb is proposing would be one in which, for every 'upload' of the file that receives a DMCA takedown notice, the associated download link could be deleted (i.e. complying with the notice as far as the rights holder is aware) but another one almost immediately created, linking to the same content.

The host could simply claim another user uploaded it after the DMCA notice was received and the original link removed.

Presumably DMCA notices don't apply to future uploads as well? That would be almost completely unenforceable for a service like Megaupload.

Edit: Just a couple more proposals for such a system. First, the link re-creation could be conducted randomly at different times after deletion for different uploads, giving the impression that it is not the result of an automated process.

Second, a host could publish all the DMCA notices they receive, providing a plausible explanation for why all the content is 're-uploaded' soon after being taken down. Surely a host can't be held responsible if its 'users' take it upon themselves to almost immediately re-upload any content taken down by DMCA notices?