Complex sentence: On August 6th 2012, he appeared on WTF with Marc Maron, both of whom appear in the documentary Alone Up There which was released on September 20th 2012.
Split into simpler sentences: On August 6th 2012, he appeared on WTF with Marc Maron. Both Stout and Maron appear in the documentary Alone Up There which was released on September 20th 2012.