Amazon's original video store, Amazon Unbox, is a lot like iTunes - you shop online and the files must be downloaded to your computer in order to view them. For many people, the service wasn't worth the effort. After downloading the large files, they could only be watched in Amazon's proprietary media player which restricted their use. It wasn't until a partnership with Tivo was announced that the service gained popularity, but even still, it lags behind iTunes. Now, Amazon is taking another...