It is nearly impossible to get these builds, and BetaGames is not going to leak them, but they have released some screenshots:
The screenshots seem legit, and they are valuable since they show very early builds of the games (except for Black Ops), and some screenshots even show Pilot Cobra level.
We could use these pictures as information source, however, we have COD:LEAK. But, Activision told wikia only to remove a screenshot of leaked build of at the time unreleased game Call of Duty: Modern Warfare 2, and they haven't said anything about leaked builds of released games.
So, can these screenshots be uploaded?