Jack Black chats with ET's Cassie DiLaura at the premiere of 'Kung Fu Panda 4' in Los Angeles. The actor shares a special message to Britney Spears after he and his Tenacious D bandmate, Kyle Gass, covered the pop star’s hit song, '...Baby One More Time,' in a video shared to Instagram. He also opens up about how it feels to be releasing another 'Kung Fu Panda' movie 15 years after the franchise’s first movie release. 'Kung Fu Panda 4' is in theaters on March 8.