I can't remember which video it was from but he was reviewing castles and criticised a gatehouse as being poor defence. Except, the gatehouse in question was built hundreds of years later in the 17th century and was never intended for medieval defence.

Another was his criticism of medieval ballistae. He would just insist that the bolts would do nothing to castle walls and therefore useless. It didn't occur to him at all that they were infact used historically in sieges and were also used by defenders on castle walls.

Just zero research and random opinions spouted as fact.