Earlier quoted context omitted.
In my fever dream version of reality the success of something like "For All Mankind" would present an opportunity to fund searching for this footage.
I read an article a while ago that concluded the tapes were almost certainly reused (overwritten).
Sadly they stopped looking when they realized that. In actuality, modern equipment could probably read and recover the previous data from the tapes, if the tapes still exist. It is very hard to fully erase data with equipment from that era.
Also I wonder if there is some Soviet storeroom somewhere that has a copy? They surely would have been listening in.