After months of rumors and speculation, Amazon on Thursday officially took the wraps off its video download store, dubbed Unbox. The service offers movies, television shows and other videos, which play in Amazon's own software player as well as on portable devices.

Like on Apple's iTunes, TV shows on Unbox cost $1.99 USD. Movies will range in price from $7.99 to $14.99 USD, with some films available to rent for $3.99 USD. Amazon is using Microsoft's Windows Media digital rights management technology for the new service.

Once a video is purchased, Amazon provides two versions, one to play back on the PC and another for portable media center devices. Unbox purchases are known to work on only six devices, including the Zen Vision, Zen Vision:M, Toshiba Gigabeat S, Archos AV 500 and 700, and iRiver PMC.

Jupiter Research vice president Michael Gartenberg criticized the service's lack of concrete device support due to problems with Microsoft's Plays For Sure program.

"We've said it before and we'll say it again. The iTunes music store succeeded because of the iPod, not the other way around. iPods drove people to the store," said Gartenberg. "Without a compelling device story (and it's not clear YET whether Zune will play protected music or video from Plays for Sure services) it's hard to see this as a real threat to Apple."

Apple is rumored to be preparing full-length movie downloads from iTunes, with an announcement expected to come on Tuesday. A number of Hollywood studios confirmed they were in talks with Apple, but per usual, the company has remained mum on its exact plans.

Amazon Unbox requires Windows XP and does not work on Macintosh computers due to its use of Windows Media DRM. A 1 hour movie will take up 1.2GB, with 2 hours using 2.4GB of storage space. Users can start watching videos while they are being downloaded, Amazon says.

"Pricing isn't likely to drive folks to use this so for now it's mostly a mobility story without a super interesting mobile device to use it with," added Gartenberg.