Found this New York Time article interesting. The author makes the point that with each successive generation of home movie distribution technology, the cost of re-mastering movies for the new medium makes studios think twice about the undertaking. As a result, the catalog of readily available movie titles shrinks with each new generation of playback medium. "[...] huge swaths of our film heritage have vanished. After 10 years of DVD the studios seem to have concluded that all the films that will make money in home video have already been released; that number is a very small percentage of their output. Turner Classic Movies online says that of the 162,984 films listed in its database (based on the authoritative AFI Catalog), only 5,980 (3.67 percent) are available on home video [...]"