As far as I know, recordings from the MW3 Vault can only be a certain (short) amount of time to be able to be uploaded. Can someone confirm the exact length?
So unfortunately for you, unless I'm wrong, you will not be able to upload a whole game at once. You could attempt to upload videos separately and then combine them--it may take awhile however.
If you are very serious about uploading games and perhaps even making commentaries, then an HD PVR is a must. It would allow you to upload whole games to your computer, where you can edit them as you want and then upload them to YouTube. However, PVR's are not cheap and if you are a casual player it is probably not a good idea.
