"I watch the movie at a theatre"
Translation:나는 극장에서 영화를 봅니다
This doesn't make sense to me. How can 나 be used with ~ㅂ니다? 나 is informal, but the verb ending is formal.
Someone answered this on another question. So basically 저 is used to lower yourself and -ㅂ니다 is used to raised the listener. If you're higher than the listener, you can raise the listener without lowering yourself, like in this sentence. (I'm a beginner but someone has already answered this and I'm just repeating what was said)
Isn't 극장 more like a theater used for plays and 영화관 like a movie theater though