Halo 3 Film Help...

Someone please help me as this is very irritating and I would really like to watch my Halo 3 films again… a few months ago I tried to watch an older video of HALO 3… and it said the film was invalid and may be from another version of halo 3 or damaged… and worse yet is it does it with every video! I am currently playing offline have been for about a month and a half maybe? Don’t think that should really matter though. If I save a video now though I can watch it just fine. I have like 5 films I’ve saved in the past about month playing LAN and I can watch them perfect but every other video I can’t watch someone please help!