So no, this is totally ineffective. And it's not like there's actually a problem. There's no crisis of messed up kids or young adults. We all had access to porn in some form and we all turned out fine. I used to watch the late night pay tv which was just 'scrambled' by removing the sync signal. It was easy to put that back with some electronics chops. I saw my share of gangbangs and cumshots and I did not get messed up or get weird ideas. In fact I often get compliments I'm a sensitive and caring lover. I never do or push for the dirty porn tropes (unless she asks for them :)
So did most of my school friends. Also video tapes got passed on at school and later CDroms (when the writable DVD came I was already an adult). We all had plenty.
This is all to mitigate a "crisis" which doesn't actually exist.