Early this past Monday morning, I stumbled on a great blues show that our local PBS station, KERA/Channel 13 is currently airing: Soundstage: Chicago Blues Summit. It was filmed in 1974 and centers around Muddy Waters. Also appearing are Willie Dixon, Dr John, Junior Wells, Koko Taylor, Mike Bloomfield, Nick Gravenites, Buddy Miles and Johnny Winter.
You can see a preview here: http://video.pbs.org/video/2365431786/
It's scheduled to rebroadcast on the following dates and times: