Gear Gods mastermind Trey Xavier is here to show you how Metallica writes their songs. Granted it's not like Metallica came down and told Xavier personally how they do it, but given the end "Metallica song" that Xavier came up with, I'd say he gets pretty damn close!
It also helps that he's got some James Hetfield-looking guitars to accompany the video. Ditto for the very convincing Kirk Hammett and Robert Trujillo costumes.