Hello Chester--my apologies for the delay in my reply to your request (6 months!?)
The entire series came out on HBO Home Video as a 13 volume vhs set--I just checked Amazon and this set is now very expensive.
I know the entire series was about to be released on dvd around 2003 when plans to release it were dropped very suddenly--when someone asked Kevin Brownlow who made the documentary what happened, it seems that everyone who had clips in the series now wanted to be paid for them.
I remember Duke spoke about his early days in Hollywood and gave a heartfelt tribute to the work of one of his idols, Harry Carey--he spoke of how he got to know Harry and Olive (she was also interviewed for the show) and how he made an indirect tribute to Harry in the final scene from "The Searchers" (which was included in the show....and most likely, Warners would like some reembursement if this show with this scene ever appears again!)