I used the film viewer to look at a bunch of AHF files I made 5+ years ago, and they ran just fine. The only hiccups came from maps that didn't match up, but that didn't impact the actual flying part of the films at all.
I find some won't load at all. Some will load, but playback doesn't follow what really happened, and then some if you so much as take a single bullet it reduces you to a flaming, smoking, wingless tailless husk of a fuselage, and sometimes any other planes as well.
Not to mention all the terrains have changed. I replayed one really memorable FSO after the fact and was disheartened to find the thrilling through-the-foothills twisting and turning knife fights were now 500+ feet above the ground because the terrain was different.
It may think it loads, but it won't play back properly.
