A video is circulating of Stranger Things actor Joseph Quinn rehearsing his viral heavy metal moment. In the Stranger Things Season 4 finale, Quinn's character, Eddie Munson, plays Metallica’s track ‘Master Of Puppets’ to help save his friends. There has been much speculation over whether Quinn actually played any of the songs himself, but new footage shows it's clear that Quinn learned the song for the scene. The video shows Quinn, out of character, finding his way around the metal classic. What's the hardest thing you ever had to learn how to do?