The fourth CG episode is out for Halo 4: Spartan Ops.
Halo 2 Anniversary - CG Cinematics
Enjoy 49 minutes of CG created by Blur Studio for the Halo 2 Anniversary.
Making Halo 4 - Part 1 and 2
Join 343 Industries on a 20 minute behind the scenes featurette on the creation of Halo 4.
Halo 4 Trailer VFX Breakdowns by Method Studios
Method Studios do VFX breakdowns of several scenes from their recent cinematic trailer for Halo 4.