If you buy your entertainment digitally, you really should read this story from Boing Boing that was published over the weekend:
Bill sez, Last "December I bought some favorite Christmas specials for my kids with the idea they could watch them every year. Went tonight to watch one ('Disney Prep and Landing 2' if you're curious) and it was gone from our library and couldn't be found on the site at all. Amazon has explained to me that Disney can pull their content at any time and 'at this time they've pulled that show for exclusivity on their own channel.' In other words, Amazon sold me a Christmas special my kids can't watch during the run up to Christmas. It'll be available in July though!"
This is not just an issue with Amazon. It's got to do with any service in which you buy—shudder—"content" that comes with restrictive DRM control as part of the package. Physical media has lots of limitations, but no movie studio has ever broken into someone's house to physically reclaim a DVD. It's bonkers that this is considered to be acceptable behavior.