Yep! Definitely look them up when you see them. There are lots of rare and hard to find ones... I focus on things like Criterion, box sets and anything that looks 'odd'. I picked up a five disc Anchor Bay set of WWII movies for $4 and they sold for nearly $15 each.

Don't skip on CDs, VHS, Cassettes or vinyl records! Though be sure to check the condition and that the correct disc is definitely in the case before you buy it.

Vinyl records are difficult to grade, so I would avoid them unless you can play them and reliably grade them OR they're sealed OR the surface on both sides appear immaculate. Sadly, they usually just add to my already overstuffed vinyl collection instead of winding up on eBay.

VHS and audio cassettes are hot right now as well, so if you see some classics, definitely give them a look on eBay before you pass on them. They usually have a barcode.

Typically someone will drop off their whole collection at place, so consider buying items to sell in a 'lot'.

A complete hardback Harry Potter book set is $100+! (usually $2 a piece at my thrift shop) I almost have a complete set from my many trips to the thrift store, so pick them up when you see them!

I think a lot of people like the hobbyist collection aspect of DVDs. There's also a pretty significant contingent of people who want access to films that have no (or no consistent) streaming options. Also, lots of films and TV shows that do not have licensed content.