General Intelligence Utility Function
The difference he is making is between long-term and short-term goals. Both need to be definable, and there is obviously a mutual dependency between these two sets of goals, so you can think of pressing the red button as something that will also have to be treated within this framework. You can then imagine that if pressing the button has the same utility of your present long-term goal, that would cause the button to be pressed imediately, whereas if it had the same utility of any of your immediate and cheaper short-term goals (because it would be normalized that way), it could ideally go unnoticed, meaning that it would be made uninteresting as an action, but not as a result. He then immediately addresses the need to consider the existence of the button in long-term goal scenarios, so there's no free lunch here.

This is evidently an oversimplification made for didactic purposes. The idea is not to show exactly how difficult is the problem, but that it is more complicated than common sense would conceive.