Wow. eBay needs to recognize that their profit margin is affected by both the buyer and seller. Screw sellers, and they won't sell. It's tough to find that happy median. Did you try and send eBay/PayPal before and after pics? Like, pictures of the items you sold him versus the ones you got returned? If they were damaged during shipping to him, UPS would've (1) recorded said damage and (2) ponied up costs because I think all items are insured when shipped, correct? Anyways, that is a plain tragedy.
Pirated DVDs are a big issue. That's why I like using trading services like Goozex. If someone sends a pirate to you, give them a negative feedback and ship the item to Goozex. You get all your "points" (money) back and that user is significantly impacted, if not banned.
You can always notify the FBI as well. I've done that twice now, and it makes for some great lulz when you see the seller disappear from eBay and a letter following up on your charges.
I have several types of mailing scales (one 0.01lbs to 3lbs, one 0lbs to 10lbs, one 0lbs to 30lbs, and one 0lbs to 300lbs), so if I ever get a returned item, before opening the box I would weigh it. Empty boxes are very very light. If what I'm expecting weighs a solid 20 lbs and it doesn't even budge my 0-300 scale, then I'm grabbing a video camera while I open the box.
It's a bit paranoia, but I also video tape myself packing the items. Clips get deleted as the positive feedback comes in. To date I haven't needed to use them since most of my winners probably come from the boards I advertise on (and are therefore collectors who understand how to do good business), but they're there just in case.