This was featured on the HBO documentary series "Pornucopia: Going Down in the Valley". The documentary led my wife and I to believe that it was a normal couple who wanted to star in a porn film with an established porn star. That is, true amateurs on a working vacation of sorts.
Apparently not true. The "normal couple", Yasmine and Vincent Vega, have been in porn films both before and after "Screw My Wife #4". Particularly Vincent, though I don't know why. Yasmine was far more alluring.
But that's only me. My wife might have a different opinion.