Charles W. Mills (2005) "Kant's Untermenschen". In: Andrew Valls (ed.), Race and Racism in Modern Philosophy. Cornell University Press 169--93.
This audio recording was uploaded as part of the required reading for Module 0: Ending The World's Session 2: Who's Human? organized by Decoloniality London.
Full text can be found here: http://www.decolonialitylondon.org/decolonial-study-programme/module-0-ending-the-world/session-2-who-is-human/
More info: www.decolonialitylondon.org