Video tape isn't really that durable over time. Most of the info I can find comes from digitization services, but they are fairly consistent in saying that, for tapes that are stored in "normal" conditions, you can expect 10-25% degradation in 20 years. These tapes are 40 years old. They have likely degraded significantly already and may fall apart when played.
These bad boys have been screaming for preservation since the 90's tbh. There's no reason this shouldn't be public domain. Its our history, its computer history.