Yawn.
Biden may not remember when FDR was elected. Frankly (get it?), I don't either, but 1929 isn't terribly far off the mark. FDR was president during most of the Depression, so the mistake is understandable. Nor do I know when TV became popular (although 1929's a stretch). And I doubt you do, sans Google, either.
Biden's opponent, however, believes the earth is 4000 years old.
We all get it wrong sometimes. Everything's a matter of degree, I guess.