How do I download the Halo 5 beta?

The ‘extras’ section of MCC doesn’t have it available for me. As a matter of fact, I cannot watch Nightfall either it keeps telling me to buy the game.

It’s not available yet for all players, This beta is only a test for the real beta that comes with MCC, Right now you can only get in if you were a preview program member,

The full beta starts on the 29th of December and you will be able to download it on that day from your MCC disk