As you may know -- or not -- in the original Broadway production of The Sound of Music that starred Mary Martin, the role of Captain Von Trapp was played by Theodore Bikel. While there's a wonderful cast album, there's no video footage of that 1959 production. However, I just came across a video of of Theodore Bikel from four years ago singing "Edelweiss." It's not the same, but the next thing, 51 years later..
Nice, too, is that Bikel, who is a longtime folk singer, performed his own guitar solos in the Broadway production -- and of course does so here, making it even more of an effective re-creation. What's lovely about this, as well, is that halfway through he just naturally signals the audience to join in, which somewhat duplicates the moment in the film when the Captain gets the audience at the talent show to sing along with the family and build up support and emotion for his country, after having been told by the Nazis that he had to join the German Navy after this performance.
By the way, a few years ago I heard an interview with Bikel and he spoke about The Sound of Music, and why the show was so meaningful for him. He was born in Vienna, Austria, in 1924 and said that he recalls as a young boy when a Nazi army paraded through town and saw Hitler ride by. It was long before Bikel was able to escape from the country.