Amazon has just launched their Prime Instant Video Service that basically allows their Prime members the ability to stream video on demand for free (well not really free if you take into account the $79 annual fee they have to pay for their free 2-day shipping – let’s just say no additional costs). With Amazon’s new Prime Instant Video Service, Prime members get access to over 5,000 movies and TV shows anytime, anywhere they want as long as they have access to a computer or a supported set top box such as Roku. Roku recently announced that they will be supporting Amazon’s Prime Instant Video Service and it can be accessed from the Amazon Instant Video Channel on their set top box. As of today, Prime Instant users can watch movies such as “The Girl with the Dragon Tattoo” trilogy, and TV Shows such as “Doctor Who”. Users who want a free one-month trial of the Prime Instant service can head here to sign up.