Julie Andrews reflects on her doubts about turning the Broadway musical into a film

By Lynette Rice
Updated March 18, 2015 12:00 PM

The hills are alive! As

The Sound of Music turns 50, Julie Andrews and Christopher Plummer share their memories of making the classic movie. Subscribe now for instant access behind-the-scenes, only in PEOPLE.

Julie Andrews definitely had her doubts about playing Maria the nun.

In this exclusive clip from the upcoming DVD release that coincides with the 50th anniversary of The Sound of Music, the 79-year-old actress reflects on how she had seen the Broadway musical with Mary Martin and how it clouded her judgment.

“Think about it, children, mountains, music and nuns?” Andrews says in the DVD’s extras. ” But by the time I arrived here in Salsburg for filming, I knew I never needed to worry again.”

Andrews also looks back at her work with Christopher Plummer, who played Capt. Von Trapp in the 1965 film that earned five Oscars including one for best picture.

“He brought a welcome astringency to his role,” she said.

Andrews, together with Plummer, will participate in the TCM Classic Film Festival that will run March 26 to 29 in Hollywood. The festival will kick off with a screening of The Sound of Music.

Plummer, 85, will also participate in a hand and footprint ceremony March 27 outside the TCL Chinese Theatre.

For more behind-the-scenes pictures of The Sound of Music, pick up the current issue of PEOPLE on newsstands today.