This is a possiblity, I dont have any experince with fraps. But, if you havent cleaned out the old drivers and installed the newest. You might have "Force TV-out detection" On in the drivers, and with nView, you can only watch a movie on one or the other, not both. Reguardless if its cloned or Dual View.
What Im saying is, if the drivers think you have a second display, It might be playing the movie on that "fake" second display. Just make sure you have your Monitor set as your primary display.
I had this issue awhile back with Winamp and my movies....It was playing on my TV, that wasnt hooked up at the time.