It seems obvious to me that few people would watch TV commercials during DVR playback (and likely you too, astute blog reader!), and in the 10/22/08 prime update by MAGNA (page 4), there are more numbers demonstrating it. The numbers I've taken from the report below show the Live Program rating, the Live+3 Program rating (including average program viewing within 3 days of the initial broadcast) and the C+3 Commercial rating (which reflects viewing to the average commercial minute up to 3 days after the initial broadcast).
While DVR playback increases average program viewing between 7-20% in the 3 days after initial broadcast, only in the 12-34 age group do more people watch commercial minutes in the 3 days after airing than during Live broadcast, and only a 5% increase at that (compared to a 20% increase in program viewing). In the other age groups the additional program viewing resulted in either no increase or a reduction in the amount of commercial viewing. So that DVR viewing isn't adding any commercial viewing to their shows. And while the brodcast network PR departments would like you to believe that DVR viewing ads value to their shows, advertisers aren't paying for those DVR viewers.
5 Network Average Ratings (September 22-28, 2008)
|Age Group||Live Program||Live+3 Program||C+3 Commercial||DVR Commercial Viewing (C+3 - Live)|
Nielsen TV Ratings Data: ©2008 The Nielsen Company. All Rights Reserved.