The six major networks - ABC, CBS, NBC, Fox, UPN, and WB - plan to hold a press conference today to present the reasons that advertisers should consider DVR playback viewing when making their media buys, Adweek reports (via MediaBuyerPlanner). The move comes a week after Magna Global declared it wouldn't consider DVR playback viewing figures when purchasing TV time in next year's upfront market.

Other than for disaster-relief benefits, this is believed to be the first time the networks have made a joint presentation on advertising-related issues, proving just how important the topic of DVR playback viewing is.

DVR penetration is estimated to be only about 8 million homes, and playback viewing makes up less than 5 percent of the total TV audience. But both sides of the issue seem to desire a conclusion before DVR penetration reaches critical mass.

DVR playback data - at issue because there's no way to know just how many viewers are fast-forwarding through commercials - is complicated by the fact that Nielsen plans to offer four streams of data: one of live-only viewing minus any DVR playback; live viewing plus the first day of DVR playback; live viewing plus seven days of DVR playback; and the average of all ratings data for all but the most recent week, which would be based only on live viewing minus any DVR playback.