I don't think that tapes of those 1972 broadcasts exist. However, in a previous thread, https://www.chess.com/forum/view/general/old-lyman-video , a guy said he had four hours of broadcasts of the Karpov Kasparov battles.
G. Koltanowski's 1972 PBS TV Shows
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Hi! I'm sure some of you might remember the TV broadcast
of the 1972 title match Fische vs Spassky. There was also
a weekly show with Goerge Koltanowski as host. I remember
one when he explans his blindfold method. Going over
each board from the start, every time he returns to
a board. He held a 40 board plus record. It would
be great if a disc set was available of the shows.d
But since the Fischer boom. Maybe a bunch of us
could show an interest with PBS, if they can find it!! Rich