Tips for researching stuff on tapes

A while back I got a bunch of "Sold as blank" tapes (for a project I'm doing later on) and I wanted to digitize and archive their contents before I record over them. I may be a data hoarder, but I probably won't be keeping this stuff on the OG tapes. Unless it's something really cool. a lot of them have the commercials cut out so I'm having a hard time dating/researching most of the content on the tapes I've looked at. The ones I've seen seem to be from the early 2000s and mostly PBS content, but that's just a guess. There are 19 tapes, so yeah, if their full that's anywhere between 38 and 152 hours of content. Although the tapes I looked at looked like they where in SP so 38 is more likely. 
Do you guys have any tips/ideas for dating/researching this content? Obviously, I could just upload the captures without any info, but that isn't useful.