Sounds like a cool find. However, as Gary7 mentioned the viewing quality is probably questionable. The 3/4" tapes may be better off in a museum.
I found some Star Trek VHS tapes in the attic and was wondering if I should give them away or just take to the recycling center. Nobody watches VHS anymore, right?
If you really want to enjoy TOS, check out the remastered episodes. iTunes has Best of Vol 1 and 2 which has a lot of my favorites. It's a good buy if you don't want to purchase the full seasons.
I still use VHS quite extensively (though not primarily). So there are such people still out there. Might as well give them to Goodwill or something and get a tax deduction.