From Wikipedia:
The Ross Sisters were a trio of female sibling dancers consisting of Aggie Ross, Elmira Ross, and Maggie Ross [1] (whose real names were Veda Victoria, Dixie Jewel and Betsy Ann Ross).[2] The Ross Sisters performed as a 3-part harmony trio wherein they also danced and did acrobatics and contortionism. Their public attention peaked during the 1940s, during which they were featured prominently in the film Broadway Rhythm.[3] This footage has since gained popularity on YouTube. [4] This clip also appears in the compilation film That's Entertainment! III (1994).
Hmm...you would think 'Dixie' would have been a natural name for the entertainment industry over Elmira. Apparently Dixie/Elmira passed away, but the other two may still be around somewhere and are in their 80s.
The funny thing is that online there are some remixes of this with heavy metal music played over it. Why? haven't a clue.