Amazon brings video rental and purchases to Mac OS X as a streaming service, years after the company launched Amazon Unbox, a U.S.-only movie and television download service for Windows and TiVo Series 2 and 3 players. The new service requires a live Internet connection of 450 Kbps or faster to watch rented or purchased items.
Amazon added 24-hour extensions a few months ago, charging $0.99 for standard-definition films, and $1.99 for high-def movies.) based on whether you rent or purchase. Video on Demand rentals may be watched only through the method you choose when you pay for the rental: either online via the Flash viewer, or downloadable for offline viewing (via a limited set of portable devices, a Windows-only media player, or an appropriate TiVo model). New movies have the typical 24-hour rental period as the only option. (The standalone Vudu player that has its own video store
If you purchase a video, the content is stored in your account, and can be streamed or downloaded later to devices you control.
The Amazon Video on Demand service combines the convenience of with the range of titles sported by the . Conversely, it also suffers from the worst limits attached to streaming and computer-based viewing that Netflix now avoids if you purchase a  for use with any of their unlimited rental plans.
I have a Netflix Player, and find it fairly free of frustration. Netflix recently added a few thousand more titles for rental, which include more movies and TV shows that interest me (such as a documentary on Andy Goldsworthy I wanted to re-watch, and season two of Heroes). The quality is quite high on my 3 Mbps home DSL line for Netflix's newer titles, which were digitized well. (Some older TV shows look as though they were captured from old VHS tapes retrieved from a sales bin at a video rental store.)
The range of what's available via Amazon Video on Demand is vastly greater than what Apple has in the iTunes Store. Amazon currently counts 14,500 movies for purchase or rental and 1,200 TV seasons (not episodes), including episodes that are just hours or days old. It's possible that Apple is once again receiving the short end of the stick due to the movie and TV industry's worry that the iTunes Store would repeat its music success with video, and thus become too powerful (see "," 2008-02-06, for the story of how the music industry is withholding DRM-free music from the iTunes Store as a way of propping up competitors).
Amazon supports Mac OS X via a Flash browser plug-in in Safari 2.0 or later and Firefox 1.5 or later, and thus doesn't list a minimum system release, but rather. The company says a Mac with a PowerPC G5 running at least 1.8 GHz or an Intel Core Duo rated at 1.33 GHz or faster is needed. (Windows users need a 2.33 GHz Intel Pentium 4 or faster, and can also use Internet Explorer 6.0 or later.)
If Amazon can meet the quality bar set by Netflix and Roku, then I could see renting and purchasing movies via Amazon as yet another option. It's unclear whether streaming will work well when traveling, as it's often hard to get 450 Kbps to yourself on any kind of hotel, airport, or hotspot connection; that's where iTunes downloads (downloaded before you leave) have a distinct advantage.