(Via Jessica Duchen, British music writer and Korngold biographer.)
In this 1944 radio interview in English, Bela Bartok discusses the pieces in an upcoming recital by his wife. At this time, he was suffering from leukemia and had a little over a year to live. Bartok’s English is fluent, but his accent charmingly has a little Peter Lorre flavor (make that “Peter Lorre impersonator” flavor, since the real Lorre had an additional Viennese sound that Mel Blanc et al. missed.) Bartok speaks in some detail about forms and folk influences of these pieces.
And here’s a short video of Sergei Prokofiev playing the piano and talking about what he’s composing. The excerpt is from Scene 5 of his opera War and Peace, which had just had a partial concert performance in Leningrad. At that moment (the middle section of the waltz), Anatole Kuragin has been going after the engage Natasha, and he gets her alone to kiss her and hand her a love letter. The entire scene IS the waltz, except for Natasha’s interjections in her own musical style, which wane in strength as the scene goes on.