Not a movie, but Warcraft 3 tried hard to convince you that Arthas was doing wrong things, when most of the things were pragmatic decisions.
The big one your supposed to think is the fork in the road where he, a paladin pledged to the light, had lost his way is when you discover a city you are trying to save from the undead is infected. Everyone in the city is dead, they just don’t know it yet. And when they die they will turn into more undead for an already stretched thin army to fight against. An entire city worth of fresh dead for the undead legion.
So Arthas takes his army, burns the city, and purges/kills everyone within, so that they do not suffer undeath, and those yet living don’t have another horde of dead to struggle fighting against. The people there don’t know why they are being killed, but are we supposed to believe that if Arthas had time to explain they’d want to become undead?
Whole thing was him doing the objectively correct thing, getting rightfully angry when his subordinates lack the conviction/loyalty/discipline to do what was best for all living people in the realm. And we’re supposed to think HE is the one who is wrong.
Nah. Miss me with that. Arthas did nothing wrong. Until later, when he did. But not when he burned that city.