In 1961, Mel Brooks & Carl Reiner began a series of comedy albums that told the story of The 2000 Year Old Man. Brooks played the title role, interviewed by Reiner.
Someone convinced Brooks & Reiner that this would make a good animated special. This aired in January 1975 on CBS, and I think it was never rerun.
This would serve as Reiner's first cartoon work since Linus the Lionhearted a decade earlier. As for Brooks, who was in the midst of a very successful movie career, this was the start of a television comeback (he co-created Get Smart, among other accomplishments), which continued that fall with the short-lived When Things Were Rotten. However, it'd be more than 30 years before Brooks would do an animated series for television again, adapting his film, Spaceballs, into a short-lived series.
From the sound of things, this might have been a direct adaptation from one of the albums, judging from the laugh track.
Color me unimpressed.