I'm not sure how IPFS addresses this, but one method is to have an oracle that reports DMCA takedowns. Nodes can achieve takedown compliance by subscribing to the blacklist.
Obviously there are lots of technical challenges. Just a few:
- Who gets to add entries to the blacklist? - How do infringement victims know that's the right person to contact? - How do you avoid creating a central point of failure? (at minimum nodes need ability to choose their blacklist provider) - Since it's all content-addressed, how do you handle near duplicates? e.g. same movie encoded in different formats (basically have to punt on this one unless you implement some kind of contentID, which is a whole other problem)
Anyway, you need to have some figleaf policy so people have a clear way to opt-in to compliance.
I would be completely skeptical of this approach except that it appears to work for adblockers. Extensions like uBlock Origin let users choose from a several third-party blacklists, with sensible defaults. Of course, there are fewer ad servers than pirate movie copies...