You have to hand it to Microsoft and Bungie, they spare no expense on the marketing of their Halo games. Gone are the typical ads featuring scenes of in-game play, instead replaced by live-action ads that are more akin to short movies than commercials. The last such ad, called Birth of a Spartan, gave a little insight into the team you will be a part of. The newest trailer is a bit more subdued, but it does offer bit of background.
In the newest clip for Halo: Reach uncovered by Kotaku, you won’t find any massive explosions, just a look at life for average soldiers on the planet Reach. It also mentions what may be a plot element- the attack of a military convoy by “human insurgents”.
It isn’t flashy, but it does add more depth to the world of Reach. Expect to see more of these soon.