Watch full movie online. Metal Evolution: Extreme Metal is the definitive documentary episode exploring the musical history of metal's most underground sub-genre. Featuring candid interviews, never-before-seen archival material, rare music clips and travel footage from around the world, the episode will bring you closer to the personalities and historic locations of Extreme Metal than ever before. This episode will give testament to metal's most misunderstood sub-genre, thrilling both die-hard metalheads and the general music lovers alike.