Greg,
The code wasn't strictly necessary. Once you ordered 3 HD DVDs or Blu-ray discs (or a mix of those, and there were other "entries", like ordering a player) you got the deal.
So you could also try it that way: go through the whole process of ordering 3 HR discs, stopping just before the very last step (actually placing the order). That will show the discount
if the system would grant it to you.
(Of course you could order anyway if you so like.

)
But as I said: I don't think it will still be valid, even if it's worth a try, IMO.
Cees