Like a VCR tape, a DVD disc can contain an entire movie. However, there are major differences. First, a DVD's video quality is significantly higher (about 500 lines of horizontal resolution, as opposed to a VCR tape's 240). Second, you can reach any part of a DVD significantly more quickly, by moving a head across the face of a disc in a fraction of a second, as opposed to winding or rewinding a tape for up to a couple of minutes. Of course, rapid access is far more important for the interactivity that characterizes multimedia than for playing an ordinary movie. In addition, a DVD is somewhat cheaper to manufacture, is smaller and lighter (reducing transportation and stocking costs), and is less subject to destruction by rough handling.
Nevertheless, few video stores will make movies available on DVDs until lots of potential customers have DVD players, and few consumers will buy DVD movie players until nearby stores stock discs to play on the players. This classic chicken-and-egg problem slows the growth of any new consumer technology, unless everybody suddenly starts to believe that everybody else believes that the technology will take off.
A new form of DVD, called Divx or digital video express, has made non-believers of both store managers and consumers. A Divx DVD contains video that is enciphered in a way that only special Divx players can decipher. One of these special players will let you play a Divx movie for 24 hours after you first pop the disc into the player, as many times as you want. After that, the player will let you play the movie again, but shortly after each play it will place an 800-number telephone call and charge your credit card for the play. If it can not get access to a telephone line to make that call, it starts refusing to let you play the movie again.
Why would anybody buy a Divx disc rather than an un-enciphered disc that will play on any player, as many times as desired, for as long as desired? Because the Divx disc costs only about $3.00, whereas a normal DVD costs about $25.00! Remember, this is the age of information. Intellectual property is valuable, whereas materials and manufacturing processes are cheap. In this case, the movie on the disc is valuable, whereas the plastic of which the disc is manufactured and the manufacturing process that replicates the information are both virtually free. For $25.00, you buy the right to play a normal DVD forever (although not, for example, to charge admission or play it in a public place); whereas for $3.00 you buy more limited rights to the intellectual property.
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