Amazon is rolling out a new video service today that will either replace or compliment the Amazon Unbox video download store. While Unbox customers have to wait for a video to download before they can begin watching, Amazon Video on Demand will let you begin watching as soon as you've placed an order.

The New York Times reports that Amazon is launching the service for a limited number of customers today, with a wider release scheduled for later this summer. The Amazon Unbox web page has a little button asking for volunteers for a new beta program, so I'm going to go out on a limb and assume that beta=video on demand.

According to the article, videos will be available for rental or purchase. And once you've purchased a video, you'll be able to watch it from any computer. No software installation necessary. In other words, it sounds like the new service is browser-based.

On the one hand, this means Amazon Video on Demand will be compatible with Windows and Mac machines (I'm not going to hold my breath for Linux support), which is great. But it's also nice to be able to save a copy of a movie on your own computer for archiving. What happens if Amazon kills the service in two years. Does that mean you lose your online video library which you've paid for? I'm hoping that Amazon still gives users the option of downloading movies, even if not everyone will need to use that option.