Letterman BeatlesAmerican popular culture was altered forever 50 years ago this Sunday when four mop-topped lads from England hit the stage at the Ed Sullivan Theatre in Manhattan. More than 73 million people watched in glorious black and white. A half-century later, the two surviving Beatles returned for a chat with the room’s current occupant. Here’s a clip of David Letterman talking with Paul McCartney and Ringo Starr about that landmark night and the landmark theater where it all went down. After the jump, watch McCartney tell a funny story about how a Teamster made him nervous backstage during a later Ed Sullivan Show appearance. The clips are from The Beatles: The Night That Changed America, which CBS is airing Sunday night: