The full trailer has been released for Halo 4: Forward Unto Dawn, an upcoming series taking place before Halo 4.
Halo Nightfall - First Trailer
The first trailer is out for the Halo Nightfall movie.
Halo 4 Spartan Ops - Episode 2
Here is the second CG episode created for Halo 4's Spartan Ops.
Making Halo 4 - Part 1 and 2
Join 343 Industries on a 20 minute behind the scenes featurette on the creation of Halo 4.