I just got my answer.
Because it’s Father’s Day, the host Ben Mankiewicz invited his father, Frank, to co-host with him and program the films! And before and after, they talk about the movies and related things.
For those who don't know, Frank Mankiewicz was the song of Herman, who wrote Citizen Kane, and the brother of Joseph, who directed such films as All About Eve and Cleopatra. He himself had an illustrious career in politics, among other things being Robert Kennedy's press secretary, campaign director for George McGovern's presidential run and being on Richard Nixon's infamous Enemies List.
I only caught the end of their discussion about Citizen Kane, but the talk before All the King’s Men (that dealt as much with politics as movies) was absolutely wonderful.
Coming after that are To Kill a Mockingbird, and then The Kid. Whether these are part of Mankiewicz Programming, or TCM taking over at this point, I don't know. (From what I can tell and have tracked down, I think they're TCM-selected for Father's Day.) Whatever, here's a nice article about Mankiewicz father and son, and a good Q&A with Frank Mankiewicz.