My theory as to why film sharing is gone, if it is true (repeating from twitter):

Inter-version compatibility. Considerable work had to be done in Halo 3/Reach/4's TUs to keep old films working. The way game films work is they actually 'play' the game, and since the engine can be made to act predictably, everything explodes/blows up/hits/collides the same way. So for example in Halo 3, they actually had to fix the flying bodies bug, then go back and make it so the bug triggered if you were watching a 1.0 film. Stuff like that. In theory if they let you, you could drop into a film being played and kill the players as if you were actually playing against them, but then the film would break :bigfrown: In the same vein, if you make the Carbine fire more slowly, or change the damage or animations of a gun or a vehicle, the old films will too, and they'll desync pretty quick.

Anyway. I'm guessing they want to be able to patch the MCC at a whim, and not have to maintain film compatibility between versions, so the feature dies. This is the sanest, cleanest theory I can think of. If films can be loaded and show up in recents, that makes the actual files themselves are being generated. And they're the same as normal film files, so it's not the film format breaking, they exist. The engine doesn't care if you're loading the film from recents or saved, it's the same data. The only reason I can think of that you're not allowed to keep them is that compatibility issue. Every other file type can still be shared. Screenshots are just jpgs, no compat patches needed. Game types are set in stone and 4's gametypes already support new dynamic data being added, so no issues there. You can change the actual .map file and a Forge variant won't care, as long as the internal names match, so no issues there either.

As to why Halo 3 Campaign films are dead, the most likely reason is that the new MCC skulls (or other new functionality) were not made compatible with film playback. Easier to cut the feature when strapping new functionality onto the old engine.

Also, this would mean in it's current state, a theoretical ODST in the MCC collection would have no films either - both Campaign and Firefight run off the same engine, and ODST runs off the Halo 3 engine.

This of course, all depends on that manual being accurate.