Terry Sanderson pointed me to a recently-posted Polskie Radio interview that Marlene Dietrich gave during her first Warsaw concert appearance in 1964, which you can hear here. Typically, introductions and commentary are rife with well-known biographical facts, but hosts Anna Piwowarska and Peter Gentle share Poland-related Dietrichiana that make the entire program--not just the 1964 interview--worth hearing.
With anecdotes from Angelika Kuźniak's Polish-language biography on Dietrich, Marlene, the hosts blend the personal with the professional. Gentle calls Dietrich "eccentric" for bringing 35 suitcases, claiming to have thin eyelids, and cleaning her hotel bathroom with chloroform. Piwowarska speculates that Dietrich banned photography at her concert because the flash cameras would have exposed her mythical foundation. Imagine what Dietrich would do if faced with the TSA's full-body scanners!
Piwowarska and Gentle relate many more stories, but I do want to highlight a professional and Poland-related one: Czesław Niemen led Dietrich's warm-up band and performed "Czy mnie jeszcze pamiętasz?"--a song that Dietrich later recorded with self-penned German lyrics as "Mutter, hast Du mir vergeben?" EMI has already had this Dietrich track removed from YouTube, as far as I can tell, but you can purchase or preview it on Amazon.
Regarding the interview, Dietrich mentioned that she enjoyed the vodka and Russian champagne, that she took a trip to the Warsaw ghetto, and that she and Polish audiences shared a mutual love for sad songs--which would explain why she took to Nieman's song. While listening to the program, I also realized that the archived footage audio was used in Schell's documentary. I never knew that Dietrich was speaking to a Warsaw audience in that clip! By the way, Piwowarska stated that Dietrich conducted interviews in French and German, so Polskie Radio's likely got more in their archives worth exploring.
So much is said, so do take a listen! Oh, and if you want to see a photo of Dietrich from her 1964 Warsaw trip, see this Flickr link. For another clip, watch this.