The DVD company sold the debt to the collection agency who reported it to the credit bureaus. You can try to dispute the item, but probably won't get very far. The DVD company says you have an unpaid debt and you no longer have any record showing you cancelled or returned the unwanted DVDs. It boils down to a dispute with the original creditor.
Derogatory items age off your credit report 7-1/2 years from the date of first deficiency. This is per the FCRA and nothing restarts this clock.
The Statute of Limitations (SOL), the timeframe to bring lawsuit, varies from state to state. Typically the SOL starts from the date of last activity or last payment. Making a payment can restart the SOL. Folks often mergen and confuse the SOL and the reporting period. They are two completely different things.
You may want to think twice before disputing this item with the credit bureaus. You may open a can of worms with this collection agency -- they are not one of the nicer ones. There is no requirement for them to contact you before reporting the defaulted debt. The FDCPA does require them to send written validation within 5 days of initial contact. However, that validation is basically the amount, the original creditor, dates, and notice of your rights to dispute.
The ONLY way you will be able to get this removed is to negotiate a pay for delete with the collection agency. Offer 10% to 20% to expedite removal, but specifically indicate that you are not acknowledging the debt. Get it in writing and do not give them direct access to your bank account.