I never had that many CDs and DVDs to begin with. When I really started getting into music in a big way Napster was huge and I didn't know anything about sound quality. Then, later, iTunes showed up or I bought downloads from a band's site.
With DVDs, half of my DVDs have an English region so it's nearly impossible to sell them here. In the end, what I've done is mostly give away what I could to friends and family and the rest (which is barely anything) is in storage.