What are after market DVDs?

I emailed a rare movie dealer on line (waltdisneydvds.com) and asked them how they could supply "genuine" disney dvds i.e. "Beauty and the Beast" without any affiliation from Disney. After checking the BBB website I see that they were rated a C-. I have since decided not to purchase from them bc BATB is coming out of the vault next year and their site does not offer a "genuine guaranteee". They emailed me back and told me that the DVDs are "after market" imports from Canada and they told me that most vendors who sell old or "vaulted" Disney Movies usually do this. I looked up after market dvds but found nothing. What are they and how are they different. This website smells like a scam and I will not be doing business with them. Im just trying to get all of the clic Disney movies for my daughter and she is missing a few that wont be sold again for a few years.