On December 18, Machine Head frontman Robb Flynn played a virtual “Acoustic Happy Hour Xmas Extravaganza” set. The performance included various Machine Head tracks as well as covers of Green Day’s “American Idiot,” Judas Priest’s “Breaking the Law,” Metallica’s “The Memory Remains,” The Eagles’ “Hotel California,” Pearl Jam’s “Black,” System Of A Down’s “Aerials,” Nirvana’s…