Y'know, I thought this next entry had been screened for schools, and maybe it was, but Energy: A National Issue is a syndicated special that made the rounds between April & November 1977, though it carries a 1976 copyright date.
It's also a non-canonical Flintstones special, though it only features Fred (Alan Reed) & Wilma (Jean VanderPyl). This, then, would be Reed's swan song as Fred. His successor, Henry Corden, steps in when Fred sings, and there you can tell a distinct difference in the vocals. Movie legend Charlton Heston narrates.
No, it doesn't look like Fred & Wilma are in Bedrock at all, but rather are our, ah, tour guides, as it were.