In the UK there is a service called Music Magpie, they buy your CDs/DVDs in bulk (there is a smartphone app for you to scan the barcodes and create an online order) and you post them in bulk. So it's quick and I believe they pretty much buy any CD or DVD. However, for most items they will only pay something like 25 pence an item.
What I might do, as it will not be worth the time to try to sell many items individually, is scan them all with a bulk service like that. Then if any show up as having reasonable value I'd look at selling those individually. The rest I would just sell to a bulk service. The majority of CDs and DVDs that are a few years old are effectively worthless, so there's not much else you can do I think other than donating them.