If you beat Diablo on Normal mode with any character, you won't unlock Nightmare mode unless you have completed EVERY act/quest in Normal mode. After you kill Diablo, you will get the message "Nighmare mode unlocked" and the credits will roll, the game will return to Act 1 Nightmare Mode, only for you to see that your character has "Nightmare mode Not Unlocked" in red text and you cannot start the game unless that character leaves. You must complete every act/quest on Normal to get Nightmare, not just kill Diablo.
Tried multiple methods of boosting inferno almost a week before the game came out, if you really can do this upload a quick video showing how?
Not saying I don't believe you, just saying I've tried a lot of different methods and so far only modifying the characters actual Act progression is the only way I've managed to boost to Inferno :(