This past Tuesday, Amazon revealed that it had signed a deal with UltraViolet, a cloud-based video format that lets users view a downloaded or streaming video via multiple devices.While the Hollywood-backed service has been around for a little while now, it hasn’t really taken off, and Amazon is the first major online video supplier to ink a deal. UltraViolet lets users combine digital purchases from any retailer and store it in a “locker.” More over, it can be used by multiple members of a family, and each family member can personalize their cloud-based list of videos.This seems like a solid solution to consumers’ desire to view movies on a multiplicity of devices. The problem is that because Hollywood waited so long to provide a digital solutions, online retailers like Amazon and Apple already have their own locker (albeit, not as multi-user or mutli-device friendly). BestBuy and Walmart have endorsed the service but have not made it an active option for their consumers.Most notably, the service does not require a subscription, which may be bad news for subscription sites. Hollywood hopes UltraViolet will encourage people to go back to buying rather than renting DVDs, which may just happen — if you have a portable locker, downloading favorites and buying one-offs of streaming video may be more favorable. But the service does integrate with subscription sites like Amazon and LoveFilm, so time will tell which way consumers are swaying.