Technical points aside:

I doubt those youtube historians could possibly do more damage to false history lessons, than all those cheaply made hollywood "historical" movies.

And the youtube historians I have seen, were very good. So mostly on the right side in battle to truth (dramatically speaking) and mostly not on the side of cheap effects for drama, or even intentional misleading for political reasons.

(seriously, there is nothing wrong with historic fiction - but it disturbs me deeply that a) most movies/books are not labeld that way, even if they should and b) even if it is labeled, most people probably do not notice)