The example he used was for the U.S., Social Security Applications and Claims Index, 1936-2007, where I have found some interesting facts for my family and my husband's family. (I shared one when this database was new on Ancestry.com.)
I want to share another interesting example in this database from my husband's family. Elizabeth (Girfanan or Girfanun or Girfman) Levitt was my mother-in-law's Aunt Betty.
This record, from the Social Security Application and Claims Index, 1936-2007, at Ancestry.com, shows that Sarah's maiden name was Brodsky and her father's name was Garson Girfanan (or Girfanan). Elizabeth's mother, Sarah Brodsky, immigrated from Russia as a young mother with her toddler daughter. I shared her naturalization papers here, one of which states that her husband is deceased.