Halo 4

The video linked will be available when the game releases on November 6th, 2012. Also, I have provided a text guide that shows all the terminal locations:

Requiem
Shortly after defeating the first two Hunters, go inside the building and check underneath the main ramp.

Forerunner
After your HUD starts to flicker and Cortana says it's because of her, it's at the base of a Forerunner structure. This is just after Rally Point Bravo after defeating a set of Prometheans

Infinity
After meeting up with fellow USMC soldiers, following a cutscene with Lasky, turn around before running outside and the terminal is directly behind you.

Reclaimer
Near the very end of the level, you will pick up Cortana and trigger a long cutscene. After the cutscene, fight the Prometheans that spawn and then continue through the first set of doors. DO NOT GO UP THE ELEVATOR. The terminal is on the right just before the elevator.

Shutdown
At Rally Point Delta, on your way to the checkpoint where there is an elite with a fuel rod cannon and two hunters, go to the structure to the left of the waypoint, and the terminal is behind the spire.

Composer
After killing the hunters and then going outside after a cutscene, look for the word "Atrium" written big up on a wall on the right. The terminal is located in some caves below the word Atrium.

Midnight
After the flying sequence is over, you'll fight your way through some large Promethean hallways. In the 3rd room, look behind the central structure for the final terminal.

Welcome everyone to our video showing all locations of the terminals! I would have loved to have risked uploading videos like others early. But i would like to keep my relationship with Microsoft intact

Enjoy!