For heavy online shoppers, the greatest benefit of Amazon Prime, which costs $79 per year, is the free two-day shipping. As a side benefit, you get unlimited streaming of all their movies to your computer or HDTV. That's $17 less a year than Netflix's instant-streaming service. But currently has only 6,000 titles, compared with Netflix's 20,000 or so titles.
If you don't want to sign up for Amazon Prime, you can still get 48-hour on-demand rentals, which typically cost $3.99. Or you can buy the video outright, which usually costs around $15.