What do “Toxic,” “Oops I Did It Again” and “Crazy” have in common? No, not Britney Spears but Derrick Barry, the Youtube sensation featured on TV shows like America’s Got Talent and The Tonight Show with Jay Leno for his remarkable impersonation of the princesses of pop. We talk to Barry's alter egos (Spears and Lady Gaga) before his Poplicious countdown gig.