Ok, I have a script here that plays a movie backward. See if it applies to your problem. If it works, the flash movie will start at frame 100 and plays backwards.
--this will be in the frame script--
--remember to span it across the timeline--
property pFrame
on beginSprite me
pFrame = 100
end
on exitFrame me
pFrame = pFrame - 1
sprite(flashSpriteNum).go to frame(pFrame)
end