re: When did the television medium surpass movies?

HBO became HBO by making creative, entertaining television. Other cable networks saw what Sex in the City and Sopranos did for HBO and tried to imitate it in various ways. Helping significantly, you need far smaller viewing audiences for cable so they can fore go any need to appeal to a mass demographic allowing you to make edgier, riskier TV. As long as you can get 3-5 million viewers, you have a hit on cable. Thus, you get pretty run of the mill cable networks like Sci Fi and AMC making great hour long dramas. Also, don't forget the advent of DVD's and DVR's. DVD's are a significant boon to the studio's bottom line and both of them help to make it easier to follow serial dramas, which are really the shows we are taking about making TV better than movies.