Like the past few Halo games, Halo 4 has several Terminals hidden throughout the campaign of the game. Finding these Terminals will unlock extra video content that can be viewed through the new and improved Halo Waypoint. I found three on my own during my playthrough, and even then I was looking as hard as possible to find them all.
Well the guys at Gamefront managed to find them, and have created the above video showing you exactly how to find them all. And as it turns out, I wasn't looking hard enough apparently. Also spoilers, obviously.
Or, if you're like me, you can just watch all the videos from the Terminals pieced together below. The first part of the video won't spoil anything really, as it's just setting up how the Covenant find Requiem. The rest of the clips should definitely be avoided if you're a fan of Halo lore and haven't beaten Halo 4 yet.