As was true with Halo Anniversary, Halo 4 has a number of semi-hidden Domain Terminals to find throughout the game. They contain backstory information about some of the key players in the Campaign, and will help to answer questions like "Why am I fighting this guy?" and "Who is SHE?" Once you've found them in-game, they will be unlocked (both on the Waypoint app on your Xbox 360 and on HaloWaypoint.com, buried in your Campaign stats). You can stream them from either location. If you do not have Xbox LIVE, you cannot see them at all (on the official sites).
If all of this sounds too difficult, we've made all eight Terminals available below, in a variety of HD and SD downloadable versions, plus a streaming Flash version.
HD versions are 1280x720, SD versions are 640x360.
You can view a streaming version of the cutscene by clicking on a thumbnail.
Right-click (option-click on a mac) to download.