I'm happy to play the naivete card when it comes to downloading. (If the producers didn't want me watching this CAM footage of a new release on YouTube, they wouldn't have uploaded it, wink wink.) I'm a bit more cautious when it comes to uploading.

But you're not uploading something that hasn't been, you're mirroring something that's already up.

You won't have any luck with that argument in court.

If you doubt me, see all verdicts for infringement when bitorrenting.

But this is very different: This is more like the original copyright holder putting something on BitTorrent, inviting people to download it freely, and them suing anybody who seeds it: By putting the data on a P2P protocol, you've kind of implicitly stated that you're okay with people seeding, or whatever the local terminology for the same is.

Um, no.

You have no guarantees that the content put up via IPFS is by the original copyright owner.

Thus immediately after you receive the infringing content over IPFS and start seeding it, you are infringing on the copyright owners rights. You have no recourse and no legal defenses to protect you.

Well, then, as soon as you receive notification, you can immediately stop hosting the data: it's like a DMCA takedown, but you have to send it to way more people.

Too late. Once you've retrieved content via IPFS, you are already infringing. You can still be sued, waiting for a DMCA notice won't save you.