Not very? It's hard to ignore the anime witch girls when their contributions are apparently what decides the battle. But up until that point, it's not particularly accurate. There's some surface level details they got right (ransom, the archers drawing their bows, the stakes), but overall it's kind of weird and janky. The French army seems to be primarily militia dudes from the local countryside, which is weird if this is supposed to be anything more significant than a raid. Where are the men-at-arms for either side? There's like one or two scattered around, but their absence is pretty notable. The French footsoldiers are using shields to cover themselves from arrows, which is weird. Chroniclers are pretty clear that French heavy infantry (which, again, would be men-at-arms rather than militia) did not usually carry shields and relied on their armor to handle arrows. For some reason, there are no French skirmishers and the English men-at-arms are all mounted. English men-at-arms and knights would fight dismounted and would remount only if the situation called for it. English archers did participate in hand-to-hand fighting, but they wouldn't be taking the brunt of the infantry advance like in the video. They would wait until their men-at-arms had engaged the enemy and then swarm the enemy flanks and reinforce holes in their own lines. There's also like twenty or thirty people fighting in this battle, but I'm guessing that's more of a budget issue.