"Oh that porn video of me isn't signed. My signed porn videos are over there"

How are you not seeing the obvious issues with your idea? People are not going to put compromising photos and videos on this blockchain because they are compromising. And yet some compromising photos and videos taken by other people are real. The fact that it's "on the blockchain" means basically nothing in this case.

Other users who were discussing "hardware signing" are closer to a working system. This is not a problem for a blockchain to solve.