I would sell them for as much as I could and not look back although you missed the window for them being worth something by, well, quite a few years.
But there are still some DVDs or CDs that might be worth a little more than others if they are out of print, there are phone apps that can scan bar codes and tell you the amazon prices.
Probably the CDs have more of a chance being worth something than the DVDs.
Morally, record companies were price fixing for years and a lot of musicians who sold albums barely got to see any profit from their work. Personally I wouldn't feel too bad selling them.
But that's me. Do what you feel comfortable with.
I have one backup of my files on an extra hard drive. For extra protection, I gave my files to as many friends who would take them.