When you are recording in the Film Viewer, is your graphics card on full? I take off (un-check) the fancy stuff like Anti-Ailising, etc when I fly. But When I go to record footage, I ramp everything on my Graphics card up, increasing the quality of the shots...
Something else may be the size of film you are recording with fraps (in the Film Viewer), and later, increasing the size of the film in your editor (assuming your not using WMM). That will make a film more pixelated.
Hope this help a little. Need a little more info on how you're making/editing your films.