"Brownian Movement" is clearly an art house sort of film with little in the way of appeal to the average viewer. This isn't a criticism...more a description for the sort of audience this film is trying to reach. And, like many art house and film festival movies, it will either be adored or hated by viewers.
The film has no context. Why people do what they do, you really don't know nor does the film try to convey this. Instead, the leading character just acts...and you have no idea why or what preceded it. You can assume she's unhappy in her marriage...but you aren't 100% sure and you have no idea what the husband is experiencing through much of the story. You learn about some....but it comes across very, very slowly.
Charlotte (Sandra Hüller) has many reasons to be happy. She has a child, a handsome husband, a prestigious job. But she also has gotten an apartment where she has sex with many different sorts of men. Now the men are mostly NOT attractive and the sex is very mechanical and often totally devoid of energy or connection...it just is. Because of this, there is a significant amount of nudity and adult content. But here's where it's unusual...it's not at all sexy or attractive or stimulating to watch. It manages to do something almost impossible....make sex dull and unappealing. There are also a couple times you swear that the woman is completely insane...such as when she later viciously attacks one of her sexual conquests for no discernable reason. She also appears much of the time to be clinically depressed. What happens next...well, you can see the film and find out for yourself.
To heighten this sense of dullness and detachment, the director chose to often use a stationary camera and sometimes placed it at floor level...like the super-famous Japanse director, Ozu. There also was little in the way of dialog nor energy of any sort. If this sounds like it might interest you, be my guest and by all means watch the movie. As for me....it left me wanting to watch a comedy or romance....SOMETHING to make me feel something! The basic story might have worked had there been energy and something to make the audience care.
The bottom line is that if you are looking for porn, look elsewhere....you could find so much better. And, if you are looking for a film that is satisfying to most viewers, look elsewhere....this one will likely leave you feeling confused and cold...very, very cold.