So, then, what if:

- the website is run by someone unconnected to the original
producer of the videos, who doesn't know the website exists?
- the person hosting the website got the content years in
the past?
- the original producer of the videos is no longer doing such
things, perhaps is dead or has a life sentence in jail?

Also, if we allow motivations like, say, getting high ratings and prominence on a website (and, to be sure, I haven't heard that this website supported user ratings and stuff), how about things like fame and getting your name in the headlines? Even if you're presented in a negative light, I'm sure there's a fair number of criminals who enjoy the thought that many people are disgusted and horrified by them, because it makes them feel powerful to have affected them so. Therefore, should newspapers that publish stories about horrible criminals be considered liable for encouraging criminal behavior?

I think anytime that question has come up, the answer has generally been "no". An example comes to mind: whether newspapers should publish the names of kids who have committed suicide, for fear that it would encourage copycat behavior. I think most newspapers do avoid that, but that's as a voluntary policy they adopt, and something that other newspapers would look down on you for if you did it--nothing like criminal liability. Likewise, some have suggested that widely publicizing terrorist attacks is helping the terrorists achieve their goals; but as far as I know, the media continue to publicize it extensively because it attracts a (paying?) audience. Laws criminalizing these things would probably be seen as a violation of the First Amendment.

Why are the media allowed to give criminals and terrorists nationwide infamy and attention, while a pervert is not allowed to give a CP site operator pageviews? I expect someone would argue that the media being allowed to report on everything is important, while anything pedophiles want is not important, even if it may give them a way to get their jollies without going out and doing things to real children. I have a feeling it's more about the political position of journalists vs that of perverts.

I think the arguments in favor of the prohibition of the possession or consumption of child pornography are rationalizations made up after the fact for the laws that already exist; that these arguments tend to fall apart under serious scrutiny, or to, if consistently applied, justify a much more authoritarian society than we have; that people make these arguments to defend their position, which they've chosen because of their emotions about pedophiles, which are generally unreasoned fear or hatred of a greater or lesser degree; that you see such intense hate against pedophiles because they're a convenient, safe target for hate, and some people love to hate, especially if they're contemptible themselves[1];

that this is so unreasoned that both laws and actual prosecution have fallen upon (a) drawn art of non-real minors [the U.S. Supreme Court struck down a law of this sort; other countries like Australia have not] and (b) minors sexting pictures of themselves [so now the laws are harming children, whom the law was allegedly meant to protect]; that people have probably been slower to propose and pass laws that don't charge sexting teenagers with CP because that goes against the unreasoning-hatred flow; and that authoritarians find the irrationally anti-pedophile mob useful for achieving their political ends, be it passing laws requiring ISPs to start filtering their traffic, passing over-broad censorship laws that happen to cover adult pornography or other things they dislike as well, justifying more extensive surveillance, or smearing anyone who opposes the above as being "pro-pedophile".

In short, I have a bad feeling about anyone who advocates measures against anyone who has not been specifically shown to have either abused children or knowingly encouraged anyone else to do it.

[1] Elsewhere in this thread, people have mentioned sex offenders getting beaten and killed in prison, and I googled a bit: http://www.foxnews.com/us/2015/02/16/ap-exclusive-sex-offend...