According to the article, characters in the film (who include French Resistance cinephiles) talk about the movies while dropping the names of various films and historical figures. It doesn't quite make sense to me, but like any Tarantino movie, I guess you have to see it to understand it. Here is what the article says about Pabst.
- G.W. Pabst: Famous German Expressionist director, mostly known for “Pandora’s Box,” starring Louise Brooks. Another filmmaker referenced in “Basterds” by its cast of movie-mad characters who talk and talk and talk about films when they’re not plotting each other’s demise, the Nazis weren’t fans of his Weimar era “decadence.”