Hey check this out: it's TED SHAWN, the creator of the JACOB'S PILLOW DANCE FESTIVAL, performing "Nobody Knows the Trouble I've Seen," from his Four Dances Based on American Folk Music, in 1931. On Vimeo!
It appears that Jacob's Pillow has just uploaded a shit-ton of its performance archives onto a new portal, JACOB'S PILLOW DANCE INTERACTIVE, that traces the history of the Festival (and thus the history of 20th century dance) through video clips and quick annotation.