Now you see it, now you don't.
Well, actually, you never saw it, but your brain told you it was going to be there and the disruption of expectation is what imbues the sequence with its emotive weight.
Disrupted expectations seem to lie at the heart of lots of emotional responses.
It's what lies at the heart of most jokes:
Obviously it's more complicated than this - the cultural conventions around jokes establish an expectation of the unexpected - but in essence this is how the form usually works.
Deviation is also what triggers attention - preferential looking indicates that infants spend longer looking at things that deviate from their norm.
The philosopher Daniel Dennet says that our brains are in essence anticipation machines - that a fundamental aspect of cognition is the necessity of forming expectations, based on direct or indirect experience, for how things are in the world.
Research based on this idea suggests that there are all kinds of cognitive and affective events triggered by expectancy violation - including heightened memory activity, which makes sense as your brain is re-building part its model of the world.
This is probably why comedic advertising seems to work so well - but as the film above shows, it can work on other parts of the emotional spectrum just as well.
[Thanks to ToniAnn for the link]