Buy a DVD on Amazon; Start Watching the Movie in Minutes (s AMZN) just launched a promotion dubbed Disc+ On Demand that may well be the start to the industry’s first major multi-platform retail experience. Customers who buy select movies on DVD or Blu-ray will be offered the chance to instantly watch their purchase through Amazon’s Video On Demand service. Movies available for the promotion can either be streamed through or downloaded to a PC or TiVo.

So far, only a tiny fraction of all DVDs available on Amazon seem to be part of the promotion. The site currently lists a little more than 300 titles as eligible for free instant viewing. All in all, Amazon offers more than 330,000 DVDs. Still, if you’re in the market for a copy of Coraline or Land of The Lost, you might want to check out the new offering. After all, this sounds like a great way to buy a holiday present for someone that you can enjoy yourself as well without having to explain the missing shrink-wrap plastic.

Amazon is clearly just dipping a first toe in the water with this promotion. In fact, the company is calling the free VOD a “gift with purchase,” which could fend off any legal challenges from its competitors. The company also added a bunch of legalese, stating that the “promotion is valid for a limited time only.” Disc+ On Demand is limited to standard-def streams and downloads, and customers who return the physical disc will be billed the regular VOD price.

Despite those restrictions, Amazon is likely watching this promotion closely. The industry has long been struggling to find ways to make physical discs more appealing in the age of digital downloads. Various studios have started to include digital copies of their movies on Blu-ray discs, and some reports see as many as 20 percent of all consumers making use of this feature to watch a copy of their movie on a laptop or other portable devices. However, the effect this may have on sales is unclear.

Amazon could, on the other hand, see a direct impact to its bottom line if it were to expand Disc+ On Demand to a wider array of titles. With DVD sales slumping and more and more users moving toward other non-physical formats, anything that could make a consumer shell out 20 bucks or more for a Blu-ray disc as opposed to $3.99 for a VOD rental seems like a good idea for a retailer.