The AW film viewer was more oriented toward running it while being "in the cockpit," so you could bring up maps and see the radio traffic, which you can't do in AH's full-screen mode. Also, it has quicker mouse-based manipulation of camera angles, which is very nice. The last advantage is that the AW film viewer is not full of bugs.
One nice thing about AH's film viewer is being able to run films more slowly. AW had 1x speed and paused, but nothing in between. AH film viewer has reverse, which would be very nice except that smoke trails and explosions (and ships) get all screwed up when you run reverse, so it has limited usefulness.
HiTech and Pyro were both very active Air Warrior players long ago. HiTech wrote VFilm, a gun-camera-film utility for Air Warrior.