Streep works hard to sing badly in her new film, 'Florence Foster Jenkins.' In it, she plays the title role, a character based on an actual heiress and socialite who devoted her life to music -- despite having a squeaky, screechy singing voice. Streep also discusses working with Stephen Sondheim for the screen adaptation of 'Into the Woods,' and why sometimes just being Meryl Streep is more nerve-racking than performing.