This was lost for several years. This clip was found in a warehouse in 1993, 32 or 33 years after it was originally created and first seen, by the longtime animation teammates. (They met at MGM studio and immediately knew they could trust each other.) The duo of co-producers & co-directors, William Hanna & Joseph Barbera, created their most popular program ever, The Flintstones (1960).
Daws Butler, rather than Alan Reed, provided the voice of Fred Flagstone. June Foray voiced Betty Rubble, instead of Bea Benaderet. Most sources say that Butler also voiced Barney Rubble. Jean Vander Pyl, the voice of "Wilma Flagstone" this one and only time and "Wilma Flintstone" afterwards, was the only person that was in all 167 episodes of The Flintstones (1960) series.
Jean Vander Pyl aka Wilma Flagstone (here, this only time), better known as "Wilma Flintstone", was the one person that was in all 167 episodes of The Flintstones (1960). She was also in the live-action movie The Flintstones (1994), but with a different character role. (Elizabeth Perkins played Wilma to John Goodman's Fred Flintstone.)
Hal Smith originally auditioned for the role of Barney Rubble and did a test track of his voice in the pilot. However, his voice was later rejected and was replaced by Daws Butler.