Five years ago, Comcast Corp. was the nation's 50th-largest advertiser. Comcast, now with movie, news, and entertainment giant NBCUniversal under its corporate umbrella, rose to second-largest last year behind Procter & Gamble. "Verizon is giving them a run for their money," said James Marra, advertising professor at Temple University. "It's just like Coke and Pepsi. They have to keep pace. It's like any other consumer product."