I find this kind of fascinating: The BBC erased many original copies of its old programs back in the day so they could reuse the videotapes.
They're not alone: American programs were erased, too, especially soaps, game shows and talk shows. The Wikipedia entry I link above goes into detail about which shows suffered most from wiping.
Have you ever heard of "Mary Kay and Johnny"? Me neither, but it was supposedly the first-ever sitcom, and like "I Love Lucy," it featured a real-life married couple and eventually, their baby. (Their real baby, while Little Ricky was played by five different infant and child actors.) And Mary Kay and Johnny shared a bed! Gasp!