All this talk about "it's actually about revenge being bad!" is bullshit. He's trying to trick people into watching it because it makes his peepee tingle to make them watch it
He lies to venti and that other girl's faces and say that the healer guy "never rapes anyone, he wipes her mind and makes her consent" which is still rape and it's a lie because he rapes her before the brainwashing. He recounts the scene in detail with Dick, so he didn't forget or misremember it, he's lying to them to get them to watch it.
Nick gets off on subjecting people to his degeneracy. He lies to a ton of people including Null, lying about the contents of the anime (saying to Null it's "his life", lying about the amount of rapes to Brittany venti) in the hopes he tricks them into watching child rape
I also think he thinks the rape scenes are hot