I don't think this is for marketing purposes. I don't know how these A-nation DVD's usually sell, but I can't imagine Ayu not being broadcasted makes that much of a difference? Above all, A-nation is her least interesting performance of the year. As a fan, I would much rather save my money for the Arena / Asia Tour, and if I have money left, the Countdown Live. DVD's are very expensive, I personally never buy the A-nation DVD's anyway.
Dunno about you guys though, maybe everyone always buys the A-nation DVD's and I'm just weird