The phrase "a long scene of" is correct and usable in written English.
It can be used to describe an extended segment or portion of a narrative, play, or film that focuses on a particular event or interaction.
Example: "The film features a long scene of the protagonist reflecting on their past, which adds depth to the character's development."
Alternatives: "an extended segment of" or "a lengthy depiction of".
There's a long scene of necessary explanation here.
Runner-up is a long scene of Green debating himself in an elevator.
Tarantino puts in a long scene of Budd's humiliation at the hands of his boss.
Rigid despite the lorazepam, Stanton waited for the film to begin, then waited through a long scene of exposition for the first expected laugh.
We're in B-movie international-thriller territory, where people say things like "You still don't get it, do you?" and "We lost a good man that night," and where a joltingly bloody shootout in Pakistan is followed by a long scene of comic relief in a Malaysian brothel.
But here I am talking like this is not a film that features a long scene of flora and fauna giraffes, crocodiles, orange trees, you name it emerging from people's orifices like something out of a Boschean Hanna Barbara, and, reader, that is precisely what I'm talking about.
A long scene compounded of both moods is laid down in The Big Sleep, a visit to the night club owned by the gangster Eddie Mars.
Ms. Saunders remains a marvelous performer, and in a long scene at the end of Episode 6 (a second season is in the works) she does make you care, as Vivienne goes off script during a taping and in masterly fashion averts a scandal that threatens to take down her and the loosely closeted Jared.
The episode originally had a different pre-credits sequence, which consisted of a long scene in the kitchen in which Clara informs the Doctor she cannot come and travel with the Doctor because she has responsibilities to her job, and the boy she takes care of asks if the Doctor is her boyfriend.
There is, however, an inordinately long scene of him shaving his beard down to stubble the morning after the show while, in voice-over, he discusses pretentiousness: It's dull first, funny second.
He quotes a long scene from "Zen and the Art of Motorcycle Maintenance," in which the narrator has a frustrating encounter with careless mechanics who can't be bothered to correctly diagnose his bike.
