Wow, the lipsync is really off in places. And flaming arrows?! Really?!
German Wikipedia contains illustration of flame arrows from Konrad Kyeser, who funnily enough is actually an NPC in the game. Their use for sieges and setting villages on fire seems to be historically accurate. This is what they are used for in those scenes.
Can't believe they wouldn't check such a thing given the historical accuracy of the game is one if it's main selling points.
Well, yes, but he also painted this:
Not sure I'd take his word for everything.
)
I always thought that fire arrows had to be shot from underpowered bows at close distances, because otherwise they would extinguish themselves in flight. Apparently, there were others of a newer construction that could be shot from ballistas and such.
Either way, my disbelief was more directed at their use here - shooting villagers and igniting freely available thatched roofs. (seems like a pointless waste of arrows only meant for cinematic spectacle)