A growing number of them have stopped paying for cable and satellite TV service, and don't even use an antenna to get free signals over the air. These people are watching shows and movies on the Internet, sometimes via cellphone connections. Last month, the Nielsen Co. started labeling people in this group "Zero TV" households, because they fall outside the traditional definition of a TV home. There are 5 million of these residences in the U.S., up from 2 million in 2007.

Winning back the Zero TV crowd will be one of the many issues broadcasters discuss at their national meeting, called the NAB Show, taking place this week in Las Vegas.

While show creators and networks make money from this group's viewing habits through deals with online video providers and from advertising on their own websites and apps, broadcasters only get paid when they relay such programming in traditional ways. Unless broadcasters can adapt to modern platforms, their revenue from Zero TV viewers will be zero.