My wife and I love watching porn together, provided I've been selective in the chosen material. Unfortunately, a lot of porn is of the "Suck that cock, bitch!!" variety, which must appeal to some guys, but I find it not only offensive, but completely non-sexual in nature. My wife an I have the same attitude regarding porn, which is to watch two amazingly good looking people fuck each other silly, while we basically do the same thing in front of the television. It doesn't turn me on to watch the "stud" of the movie treat the girl like some sort of braindead fuck machine, as this type of girl doesn't appeal to me in real life.
As far as jealousy issues derived from porn, we have none. My wife is generally the first to say "Holy shit, look at how perfect her tits are!", whereas I'll say "Think you could fit his big cock inside you?".