I've captured screens from many, but not all, of the individual scenes within the Halo 3 E3 2007 Campaign Trailer. Some contain things of note that have yet to be confirmed, and others show new versions of familiar objects from the Halo universe.

There appear to be three distinct kinds of scenes in the trailer. Straight gameplay footage is recognizable because HUD elements are present, and gameplay is shown either from the first person perspective if on foot, or in third person if using heavy weapons or a vehicle.

Cinematic footage, or footage of scripted events, is usually recognizable because it presents events that do not occur within the scope of gameplay and are not presented from the perspective of the player, and no HUD elements are present.

It is likely that there is a third kind of footage shown within this video: that is actual gameplay events, presented without a HUD and from an arbitrary camera position, using Halo 3's Saved Films feature. When the events shown are actual gameplay mechanics, such as infantry or vehicular combat, but the perspective is even further away from the action than when using a vehicle or heavy weapon, and no HUD elements are present, it is likely this is the kind of footage we're seeing. Rather consistently, Halo cinematics have not included significant amounts of combat, or events that could have been part of actual gameplay, with very few exceptions (the confrontation between Johnson, Keyes, and the Arbiter, for instance).

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