Before every show, Metallica like to set up a jam room and riff it out and get warmed up for their two-hour plus shows that they do.
New footage has surfaced of their jam backstage at PG Paints Arena show in Pittsburgh, Pennsylvania on October 18th, 2018 and it features a bit where the band jam on Judas Priest with Lars delivering the vocals for the track "Delivering The Goods." How do you think Lars did? The Priest cover starts at 7:30.