Amazon Instant Video is an online video store through which you can rent/purchase film and television content. The content is accessible through a variety of networkable devices, including computers, HDTVs, Blu-ray players, gaming consoles, streaming media players, and portable devices like smartphones and tablets.
Amazon Instant Video actually includes two different services. First, there's the Amazon Instant Video Store, a pay-per-use service similar to the iTunes Store and VUDU in which you pay a one-time fee for each title that you rent or purchase. You have the option to either watch a title instantly via streaming or, if you're using a computer or other compatible device with local storage, to download it for viewing without an Internet connection. TV shows are available for purchase only, not rental; once you buy a TV show, it remains in your Amazon library until you delete it. Individual episodes generally cost $1.99 to $2.99 (depending on quality level), or you can subscribe to a TV pass to get the entire season at a slightly discounted rate. Movies are available for either rent or purchase; new releases generally cost about $3.99 to $5.99 to rent and $12.99 to $19.99 to buy (again, depending on quality, see below). Rented titles will stay in your Amazon library for 30 days; once you begin playback of a selected title, you have 24 to 48 hours to watch it (depending on the title; most competing services only give you 24 hours for every title, so Amazon is more generous in this respect). Then, it will disappear from your library. Purchased titles remain in your content library until you delete them.
The second service, Amazon Prime Instant Video, is a subscription service similar to Netflix. If you sign up for the Amazon Prime service for $79/year (no monthly plan is available), you get unlimited access to all of the TV and movie titles in the Amazon Prime catalog. However, the Prime catalog does not include as many titles as the larger Amazon Instant Video Store. Pay-per-use services like the Instant Video Store generally receive new home-video releases around the same time they arrive on DVD, while subscription services like Amazon Prime and Netflix often have to wait a much longer time to receive these titles. Amazon Prime members also get free two-day shipping on all Amazon orders and a free monthly book rental from the Kindle Owners' Lending Library.
Amazon offers video titles in both SD and HD (720p streaming, 1080i for Tivo downloads), but not every device that has the Amazon Instant Video service supports HD playback. The Instant Video streaming service requires a minimum connection speed of 450 kbps, but the company recommends a speed of at least 1.5 Mbps for SD quality and 3.5 Mbps for HD quality. Many titles include a Dolby Digital 5.1 soundtrack; some content may only be available in PCM stereo.
When you buy a networkable product that includes the Amazon Instant Video service, you generally have the ability to access both types of Amazon Instant Video content. General users can purchase or rent pay-per-use titles, while Prime subscribers can also sign in and access the Prime catalog. You can check out Amazon's list of compatible devices here.