From what i've heard every week there will be a new "Now Airing" episode. If you missed it, you will have to purchase it at "Episodes on Demand". I'm not sure when they will become "Episodes on Demand". I hope this answers your question.
Currently Playing: Red Conquest, Battle for Wesnoth, and too many others.
Graal Classic ID: Blaze / Gameloft Live:Ace_97
Plus:Ace_97 / Open Feint:Ace_97 / Red Conquest: Ace_of_Spades