The Emmy Foundation has created a website called the Archive of American Television. The archive contains a great series of interviews with actors, writers, and producers from classic television.
One of my favorites from the site is an interview with James L. Brooks. Below he discusses the creation of the MARY TYLER MOORE SHOW.
The rest of the interview can be found here:
Carl Reiner is interviewed here:
These are 8-12 part interviews. They go into detail. All must watches!
More information on the Archive: