1956 General Motors Motorama
I caught part of this on Construir TV (Channel 23.3) here in B.A. It is the most bizarre thing I have seen in a long time. The lady dancing her way through dreamland is Thelma 'Tad' Tadlock. She is also in this video, which rates a special mention because it features a self-loading dishwasher (at the 8:28 mark), or as automatic as special effects in 1956 could make it.
Tork110 has collected some videos that include Thelma. I tend to take dancers for granted - of course they are talented, they wouldn't be in the show if they weren't. I forget how much talent and work it requires to make these things look good.