Render to Video
From Halopedia, the Halo wiki
"Render to Video" was announced around October 2008. Bungie stated that the feature was meant to allow players to capture in-game moments and upload them directly to their computers. The feature is quite useful to machinima producers.
It has not been confirmed on whether or not it will be available to Mac users. Bungie has stated that in order to get more minutes for Render to Video, you must buy them off of Amazon, but you cannot exchange Microsoft Points for them. However, they mentioned maybe allowing players to exchange Microsoft Points in the future.