It's the 50th anniversary of "There's a Great Big Beautiful Tomorrow," the theme from they Disney Carousel of Progress (which debuted at the 1964 World's Fair in NYC). Keith met Richard Sherman, part of the Sherman brothers songwriting team responsible for the song.
He sez, "Last month I had the great pleasure of singing 'There's a Great Big Beautiful Tomorrow' with Richard Sherman at his home. After we were done singing, he said to me, 'That's the first time I did that since Walt and my brother.' And yep, I filmed it! Coolest moment of my life. Wanted to share it with the whole world, basically."