Sigourney Weaver sits down with ET’s Denny Directo to discuss her new film, ‘Avatar: Fire and Ash,’ which hits theaters on Dec. 19. The acting icon reveals how she got into the headspace of a teenager to play the 14-year-old Kiri, and explains why working on set felt like an off-Broadway play despite the massive budget. Plus, she gives her tips on how to hold your breath underwater, as she did for nearly 7 minutes in this movie!