Exactly. The mistake is that thinking that Porn could ever be an instructional video on sex. Are there some techniques you use that are the same as porn? Of course. But it's definitely a warping of expectations and actualities. (and I'm actually not talking about the actors, that's a whole other ball of wax) I know a guy who's first time was ruined because he spanked the girl and she burst out crying. Stupid? Of course, but that's the point. He was young, inexperienced and only went off porn as his "instructional" video.
There really should be better options out there.