Comcast CEO Brian Roberts closed the annual National Cable Show this morning by giving executives a glimpse of their future transmitting TV shows via the broadband cloud. He says that some of his systems over the next several years will offer transmission speeds of more than 1 gigabite per second — fast enough to download an entire 39-episode season of 30 Rock in 1 minute and 39 seconds. “We are demonsrating a whole new level of speed,” he says. ”It’s where the future of broadband is headed.” The demo came as he unveiled some of the features of his company’s Xfinity TV service. The most distinguishing feature for consumers is that it enables viewers to search for movies and shows much they way they would via a search engine such as Google. It also can make recomendations based on data from a user’s Facebook account. “The guide becomes what your friends tell you to watch, not the linear alphabet,” Roberts says. Calling cloud-based TV a “game changer,” Roberts says that “we need to make the television feel as relevant as all of these other products” such as smartphones and iPad tablet computers.