Use only if you are talking about a specific, previously mentioned group of DVDs.

Example: "Where can I buy old DVDs you mentioned yesterday?" Where to Actually Buy Them

If you are looking for places to shop, enthusiasts on Reddit and resale experts suggest:

: If you are looking for any old DVDs (not specific ones), you use the zero article (no article at all). Correct: "Where to buy old DVDs." Incorrect: "Where to buy an old DVDs." When to Use "The"

: Vintage Stock and Movie Trading Co. focus specifically on used entertainment media.

: eBay and Amazon (used section) are the largest sources for rare or out-of-print titles.

: Services like Zapper and World of Books specialize in pre-owned media.