Spartan Ops is an episodic cooperative campaign released weekly for Halo 4 owners with Xbox LIVE Gold. One episode is released each week, broken into 5 chapters - and a short (5-10 minute) cutscene is released at the beginning of the week, to set up the current content. As time unfolds, you'll find streaming and downloadable versions of these weekly cutscenes archived here. (These are available in streaming form on Halo Waypoint, as well, along information about each chapter - but if you want a downloadable, HD version, this library is your friend.)
WARNING: Spartan Ops takes place 6 months after the events of Halo 4, so these cutscenes will contain spoilers for the regular Halo 4 campaign. Finish the game before watching these!
HD versions are 1280x720, SD versions (and the streaming Flash version) 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.