Start with Margot Robbie. She has two Oscar nominations, and even when she's in a poor movie, people like her. She looks like a movie star. She is well cast in Babylon.
Consider Brad Pitt. He has two Oscars, one for acting. He looks like a movie star. He is well cast in Babylon as a fading star.
Both Robbie and Pitt let you know that they are acting in Babylon. We don't hold it against them, because we like seeing them on the screen. But if we are to believe Babylon, movie making is quite different from what appears on the screen. Pitt's Jack Conrad can show up drunk, do a perfect scene, and go back to being drunk. Robbie's Nellie LaRoy can turn on the waterworks at will, but stardom makes her a drug-addled mess. Movie making is filled with self-absorbed, at times tyrannical people. And everyone likes to party ... it's called Babylon for a reason.
Writer/director Damien Chazelle is happy to let us know that he is directing. Babylon is nothing if not showy. Chazelle's excesses seem a good match for what ends up on the screen. He never settles for good enough when more than enough is possible.
I'm trying to figure out why Babylon seems so unlikable to a lot of people. Some critics loved it, but the consensus was less than good (Metacritic score of 60). It was a box-office flop, not even making its budget ($80 million, with a box office of $62 million). None of this reflects what I saw, a movie that is like a speed freak's version of Singin' in the Rain, minus the songs. It's all too much, of course, and that includes the length (more than 3 hours). But some of the set pieces are terrific, much of the acting and/or screen presence is engaging, and the costume and production design deserve their Oscar nominations. Babylon is not a great movie, but I don't get why people crapped on it.
Here's a clip. It is indeed 8 minutes from Babylon, but despite what it says, it is not the opening.