Red Dead Redemption Undead Nightmare Pack Question? *Spoiler*?

ok i have two questions. i bought the undead nightmare pack for 1600 microsoft points and it said it came with all the other dlc's. 1.How do i play the other dlc's that supposedly came with the undead pack, and 2. what did the little message at the top say when *spoiler* marston popped out of the ground as a zombie? somehing about a magic flask?