Television viewership continues to shrink. The week of July 4th was the least-watched week in recorded history, as only 20.8 million viewers were tuned in to primetime TV at any given moment. This was down from the previous low of 21.5 million viewers set last July.

While it's obvious why the numbers would be low (the US holiday, the excellent weather, summer reruns), the fact that records are being set shows that network TV is gradually losing its hold on popular culture. While the free networks face challenges from newer forms of media like video games, the Internet, and MP3 players, they're also competing against other ways of watching video content. Consumers can now watch TV on cable, satellite, FiOS, IPTV, and the Internet, all of which offer far more options than the over-the-air networks.

The networks are attempting to stay relevant to advertisers by changing the way they sell ads. They're stepping up their use of product placements and other forms of advertising that are less likely to send consumers reaching for the remote. Placement also helps to guarantee that commercials aren't being skipped by DVR users.

They're also making new promises to advertisers. Instead of selling 30-second spots that are based solely on the number of people watching a particular show, networks now offer "audience engagement" guarantees as well. Basically, the network guarantees that a certain number of viewers will watch a certain show intently, as opposed to simply having the TV on in the background.

For NBC, engagement will be measured by IAG Research, which will poll audience members to find out how well they can recall certain plot points and other information. The idea is that viewers who are engaged in the show will also be paying more attention to the commercials. Advertisers seem to like the new set up, and in fact have been the ones pushing for it. The fact that the networks have agreed shows exactly who's running things at the moment in TV Land.