Tenacious D: Time Fixers

Tenacious D Time Fixers is a short movie that was used as a promotional tool on the iTunes website. The movie starred Tenacious D as well as Michael Keaton and longtime collaborators Jason Reed and Paul F. Tompkins. The first half of the film was available as a free download iTunes, while the second half could only be accessed after preordering the album.

The Time Goblin, now in prehistoric times, is about to kill a butterfly to distort the future, only to be encountered and successfully killed by Jack and Kyle. Before they go back to the present, they rig time so the person who said the band sucked, Steve Johnson, will be shown his own death certificate and tombstone that exact moment.

Source: Wikipedia