Why was Dumbledore angry in the scene where Trelawney was sacked? He shouted, "Don't you have studying to do?!" at the students. Dumbledore is supposed to be a more quirky and benign character but is rather rough and unapproachable in the movie.
It should be noted that Dumbledore never says any such line during this scene in the book and it is rare for him to respond or speak with such bite to his students.
The impression that Dumbledore is angry (throughout the film and especially in that scene), can also be seen as a direct relation to the actor's understanding of the lines and the characters temperament towards others.
In an interview from right before the film premiered, Michael Gambon talks about his experience as a theatre actor and the fact that movies he has done have mostly been for money, not out of interest in the roles.
He also, in other interviews has mentioned that he has not read the books and sees no point in it, since he has the scripts. It seems reading the books would at least give him better insight into his characters development.
Following is an excerpt from the interview:
Q: What makes Dumbledore the greatest wizard of all time?
A: I have no idea. I just say what the script tells me to say. I learn the lines and say them I dont have much sub-text. Theres no sub-text in Harry Potter really, its all magic. Anything can happen.
