Just as ridiculous as a motorcycle wheel climbing water, and exactly comparable when the only justification is the vague, handwaving explanation that has been given for the water wheel climbing. I'm surprised you do not know that the pressure in the air varies with altitude. Both water and air behave as fluids in these conditions, and both have the pressure vary with depth/height. I repeat, the physics of the problem is too complicated to be settled by just a vague, hand-waving explanation. The way to settle it is to do an experiment. I have sent the mythbusters a note asking about it. I guess the more notes they receive, the more likely they are to look into it.