Complex sentence: The scene revived Hanneman's and guitarist Kerry King's interest, and since the band released a DVD the previous year-- "War at the Warfield"--they decided to add something different for the new video--raining blood.
Split into simpler sentences: The scene revived Hanneman's and guitarist Kerry King's interest. The band had released a DVD the previous year-- "War at the Warfield"--deciding to add something different for the new video, the band used raining blood.