In the first minutes of this talk, Chomsky mentions that the first line of the Old Testament is mistranslated grammatically because of the Masoretic editors putting in the wrong vowels and that it should be obvious to people who know Hebrew. What other vowel form is available for /berešít bará/?
He’s probably referring to the fact that the word בראשית is vocalised בְּראשית be-reshit (with a shva), which technically means “In a beginning”, instead of בַּראשית ba-reshit (with a pataḥ—the contraction of the prefixes be– and ha–), which you might expect based on the translation “In the beginning” to make it “In the…”
Enter “bereshit” or “bareshit” in your favourite search engine to see the many discussions on this point. The Talmudic Sages and commentators such as Ibn Ezra and Rashi considered the ambiguity of the vocalisation of that word, one explanation being that it did not refer to the absolute beginning of everything, but was merely a statement about when God turned His attention to our own world…
Since that word appears to have also sparked an interest in linguistics in the young Chomsky, as well, it clearly was the beginning in more senses than one.