Had to look - The clip is from "Broadway Rhythm". The Ross sisters "were billed as Aggie, Maggie, and Elmira but their real names were Vicki, Dixie, and Betsy. They hailed from Colorado City, Texas and were daughters of dirt farmers during the dust bowl days. They trained on their own and began working theaters and fairs in the Midwest. Pooling their money, they bought a trailer and moved to New Jersey to a trailer park about a mile from the George Washington bridge on Route 6. They earned minor roles in a George Kaufman play, Count Me In, and went on to Broadway Rhythm then Pickadilly Hayride at the Prince of Wales Theater in London. They were summoned before the King and Queen for a command performance on Nov. 4, 1946".
Dunno if the above is true or not, just what i found on the interweb.
Not one, not two, but three cute sisters who can sing, dance, scratch behind their ears with their hind paws, all the while walking on their hands, and smiling - makes the American Idol/America's got Talent crews look pretty lame.