I believe this is the same YouTuber whose illiteracy about the 1775 Bible was palpable. Without watching it, he's likely the one whose Bible preface in the fine print says "intercalary", which means exactly what mathematicians have agreed for centuries, that it's sometimes 12 and sometimes 13, on an average of (irrationally near) 7 out of every 19 years. I've reconciled with the notion that it's deliberately (about) 12-7/19, not 12 or 13.

Background evidence for this line of thought is how God likes to focus on dates that round to multiples of three, seven, or ten in the monthly cycle.

We've just had a good unfinished dialogue here about whether the "real" day starts at dawn or otherwise (Julian days start at noon). My conclusion, as with OP, is that there are several answers that all work, without contradiction.