Fuzzy '70's sports video

I noticed that a lot of old videos from the 1970’s, i.e. Bucky Dent’s thrilling home run, seem to be getting fuzzier over the years and make the players look like they got an almost furry halo around their bodies. Cecil wrote about CDs, but I’m wondering as to what is the shelf life of a VHS. And are we in danger of losing stuff we might want to keep the same way a lot of classic silent movies were lost or has this problem been solved by transferring everything we can get our hands on onto DVD?