Edward Norton is at the other end of the booth telling us that Brad doesn't like his "shit job"as a projectionist so he amuses himself by splicing frames of porno into the family films he's showing.
While Norton tells us about the process of running a booth, Brad helpfully points out what a changeover cue looks like.
A view along the booth front wall with Norton again talking to us while Pitt, behind, is looking out a port ready for a changeover. Thanks to Los Angeles Theatre projectionist Mark Wojan for pointing out where this scene in "Fight Club" was filmed. The booth scene also appears in "Projection: 85 Years of the Projection Booth in Movies," a delightful 12 minute compilation by Joseph Holmes that's on Vimeo.
See the many pages about the Los Angeles Theatre on the Los Angeles Theatres site for hundreds of photos of various areas on the building, including many more of the projection booth.
Edward Norton and Helena Bonham Carter have a bit of a tussle before she gets on a bus in front of the Olympic Theatre, 313 W. 8th St. On the marquee is "Seven Years in Tibet," a Brad Pitt film from 1997.
Another shot on 8th St. just west of the Olympic.
Edward Norton walking down 8th St. after Helena boards the bus. Again we get some of the Olympic. In the background at 8th & Broadway is the Tower Theatre. The website Silver Screens has a page on the film with several additional shots from this scene.
See the Los Angeles Theatres pages on the Olympic Theatre and the Tower Theatre for more about these buildings.
On IMDb: "Fight Club"