But she does not, actually. For 60 years, TV could be watched only one way: through the television set. Now, though, millions watch shows like “Grey’s Anatomy” on demand and online on network Web sites like Ms. Sweeney’s ABC.com and on the Internet’s most popular streaming hub, Hulu.com.

Image Jeffrey Zucker of NBC, left, with Jason Kilar, Hulu's chief. The executives would like a pay model for streaming videos. Credit... Heidi Gutman/NBC

How people watch TV on demand  and whether they should pay for the privilege  is a critical issue in the landmark deal, announced Thursday, that will give Comcast control of NBC Universal. In the deal, Comcast will become a co-owner of Hulu.

Like all its broadcast rivals, NBC rushed to put its popular shows on the Web years ago, hoping to secure a piece of the booming online advertising market and offset an eroding audience.

The viewers came in droves, but the ad revenues have not materialized as expected. By giving away TV episodes online, “the industry is literally tossing money and premium content away,” Barry M. Meyer, the Warner Brothers Entertainment chief executive, said in a speech in October.

Comcast, the country’s largest cable operator, has already been using its considerable muscle to limit how many shows are available online, lest people think they can cancel their costly cable subscriptions and watch free online. Now the company  which, if the NBC deal passes government muster, will own a piece of the biggest site that threatens to undercut its core business  is looking for ways to charge for ubiquitous access to shows.