I did a lot of search regarding this topic, in bitcoin forum there is discussion in this regard but it wandered off. I never got a solid answer from anyone and I am still searching. Seems like furion atleast is trying to include tools for the hosting providers to look for such content and take action. Many of the architecture have just reference and video/pictures are in some other server.So when the video/pictures are removed from the servers, the reference in block chain becomes invalid providing the "delete" effect .. But if they use IPFS to distribute video/image, I have no clue