From Amazon:

When you purchase select DVD and Blu-ray titles from Amazon.com you will also receive an Amazon Video On Demand standard definition version as a gift with purchase (see details). You’ll be able to instantly enjoy the video on demand version on your Mac, PC, compatible device or compatible TV when it is available.

I’ve always believed that if you buy a physical version of any type of media the seller should also give you a digital version to download at the time of purchase. Even if the digital version is lower quality than the physical version it’ll give the purchaser that extra push to buy from you and not someone else.

Instant gratification is a wonderful thing.