Plane on a treadmill .. to be on Mythbusters

[Bodhesatva]

The answers are pretty obvious here. It's kind of a trick question.

Speed is relative for all objects. Whatever speed the airplane is traveling at relative to the ground is irrelevant; whatever speed the airplane is traveling at relative to the surrounding atmosphere is absolutely and entirely what matters. 

Thus, if the airplane is moving at a speed relative to surrounding air that is suitable for take off, it will take off. Otherwise, it will not take off.