This is worth the 155 seconds it takes to watch, if for no other reason than it will bring a smile to your face.
A friend once told me that the secret of Monty Python's success was that the actors all played their roles 100% straight serious. That is, instead of trying to be comic, they were instead just trying to be the characters their lines demanded, no matter how absurd that made them sound.
Now imagine a movie trailer taking that same approach to the Monty Python's best-loved film. What you get is this wonderful little ditty, described by its creator as a "fake trailer who sells a tragic and epic blockbuster with sounds effects who goes POOOOOWWWW !"