Hollywood supplies us with those movies and they set the terms. So if we control the app and IPFS and the user just chooses how much they share, we can prevent other content being shared on the IPFS associated with the Blust app?
Technically Hollywood doesn't set the terms -- each buyer's local copyright and commerce law sets the terms of sale. In the U.S. this includes First Amendment, Fair Use, Security Research, and First Sale Doctrine exemptions for starters. Also nobody really controls what IPFS does on their node except the node owner (which is really also the case with DRM keys despite Hollywood's wishful thinking, but I digress). That said, if you use a smart contract and Filecoin to incent DRM-encrypted block distribution, then you could probably devise a method of making a specified blacklist subscription and local-node enforcement a core requirement of those contract terms. Content addressing makes it easy to create a blacklist of the known hash-ID's of files and blocks matching your undesired "pirate" or "malware" content list.
There's obviously no way to blacklist or otherwise control hash-ID's you don't have prior knowledge about, and you can't really force any nodes to spy on themselves to insure "compliance". Sony tried that with a CD injected rootkit once, and that didn't work out very well for them.