Metallica, Slayer, Megadeth and Anthrax — the “Big Four” of 1980s thrash metal — and iTunes in the U.S. have teamed up to celebrate the upcoming release of the “The Big 4: Live From Sofia, Bulgaria” DVD by offering you a FREE video download of members from all four bands performing a cover version of Diamond Head‘s “Am I Evil?”together that night. Download the video and check out discounts on all four bands’ audio and video releases that are available on iTunes in the United States here. This Heavy Metal treat is only good for one week. Download your free video now!!