Launching a TV series just on an on-demand digital service? One big media company chief executive believes a TV network is still important when it comes to advertising-promotion and discovery of TV shows.Speaking at an investor conference, Jeff Bewkes, chairman/chief executive officer of Time Warner, commented about Netflix's recent original "House of Cards" series -- where the entire season was available immediately."We don't think it's the best way to launch a series," says Bewkes. He says shows need the "water cooler" effect that comes with a network.As an example, Bewkes discusses HBO's "Game of Thrones" -- which he says is the most-pirated TV show in the world, something he admitted Time Warner needs to work on. "We have to fix that. [But] we don't want to put it up all at once. We want to have the water cooler effect -- introduce it, and bring people to it."While commenting about the high quality of Netflix's "House of Cards," Bewkes wonders about promotion and discovery of future TV shows -- especially those that exist only in the on-demand world."It's hard if you envision a world five years from now with all on-demand: How are you going to find everything? You have to use your network to launch things in a way people can understand what it is."Separately, Bewkes says the TV scatter advertising market for its entertainment ad-supported networks -- TNT and TBS -- is seeing single-digit percentage and low double-digit percentage price increases over the upfront prices set last summer. Both TBS and TNT are looking to refresh some of their programming for better ratings, he said.