old findlaw article regarding the difference between porn and prostitution
 

my immediate question is what is stopping someone from paying a porn actor/actress to do a scene/movie with a john/johnette?

does this happen? do people fund "movies" with their own capital to have sex with porn stars, and is this legal?

http://writ.news.findlaw.com/colb/20050810.html

Jenny Paulino stands accused of running a prostitution ring on the Upper East Side of Manhattan. Among other defense arguments, Paulino moved to dismiss the case on Equal Protection grounds. She claimed that the Manhattan District Attorney's office selectively targets "escort services" for prosecution, while ignoring distributors of adult films, who are engaged in what is essentially the same activity.

Justice Budd G. Goodman recently issued a ruling rejecting Paulino's claim, on the ground that pornography does not qualify as prostitution under the relevant New York statute. "[P]rostitution," said Justice Goodman, "is and has always been intuitively defined as a bilateral exchange between a prostitute and a client." Therefore, the judge explained, the District Attorney's office has not ignored one form of prostitution and pursued another, within the meaning of the law.

Seriously, now...

I don't understand why pornstars / hookers can't just download a model release have themself and a "client" sign it and be done with the legality of it all.

Seriously. Both get paid to fuck. Only difference I see between pornstars and prostitutes is that many pornstars irrationally don't consider themselves hookers.

*shrug*

That still might qualify as a "bilateral exchange," I think maybe you'd need a third party involved

Not sure though, don't know much about those laws

Bring a camera and the bellboy into the room, then ;)

yea which pushes the ambiguity even further because im sure there are adult stars who fund their own movies