Spoilers ahead! Jamie Campbell Bower chats with ET’s Will Marfuggi about the season 4 finale of ‘Stranger Things.’ The actor jokes about Vol. 2 of the season crashing Netflix upon its debut. He also reveals what part of Vecna’s appearance had to be changed behind the scenes of the climactic battle. Plus, Jamie praises the Duffer Brothers and reacts to becoming the hit show’s ultimate villain. Season 4 of ‘Stranger Things’ is now streaming on Netflix.