This clip is posted partly to provide comic relief, but also partly to make a valid point. Some job applicants come into interviews so totally convinced that they are exactly what a company needs that when they are told "no thanks", they can scarcely believe it.
This amazing piece of delusional self-awareness illustrates that we might not have any idea how we are perceived by others:
When you stop laughing at the clip, ponder for a moment the fact that professional interviewers often spend 99% of a 20 minute job interview totally knowing without a doubt that the candidate is not hirable ... but yet the candidate is oblivious to how they are presenting themselves.
A good argument for mock interviews, we'd say.
Lesson: ask others for constructive criticism before your big interview. Make sure you let the other party know that you want the unvarnished truth: what did I do well, what could I have done better, and what must I never, EVER do again.
Good luck!