The man behind the mystery -- Mystery Guitar Man, to be exact -- Joe Penna stops by the Young Hollywood Studio, rocking his trademark shades and telling us all about his 3-part webseries, "Meridian" (http://rides.tv/meridian/)! MGM also gives us the scoop on some of his favorite YouTube videos (of his own or otherwise), and then we get to show us how to pull off one of his signature dance moves! Hosted by Oliver Trevena (@olivertrevena)..