Hi Polat:
"Shutting Your Butt Down" is a common expression in American English.
It means simply; I---am---stopping----you.
However, typical of American communication, this is a very forceful expression.
As Quentin Tarantino uses it, it means that; "I am shutting you up!" or,
"The Interview is over.
The reason is that after the 4 minute mark, the interviewer begins asking the Movie Maker whether he sees a connection between people viewing violence in a Film, and people enjoying acts of violence in real life.
Quention Tarantino indicates that he has already communicated his ideas on that subject, and he refuses to discuss that question with this interviewer. Basically, the interviewer is a kind of Intellectual "Twit" as interviewers go. What he is doing is manipulating the famous movie maker into arguing that there exists a causal relationship between movie violence and violence in real life.
In other words, the Interviewer is using the time of the movie maker, to upstage the movie maker to create a popular platform for his own Pacificist worldview.
The point is that no celebrity needs to freely give their consent to an interview in which the interviewer intends to upstage them by asking deep moral and philosophical questions for which the Interviewer offers no objective data.
Moreover, it is absurd for an interviewer to suppose that Quentin Tarantino should be obligated to provide a sounding board for the Pacifist worldview of a person lacking Journalistic Credibility and also lacking in Moral Standing in the public media.
At about 5:52 into the video, Quentin Tarantino says; "I'm shutting your butt down!"