For years television executives have feared the worst of DVRs, now in nearly a third of homes, that more and more viewers would fast-forward through commercials, diminishing the value of the medium.

Those fears turn out to be well-founded. Some 60 percent of DVR users and 90 percent of TiVo users specifically skip through commercials some of the time, according to separate studies by Magna and Starcom, respectively.

But the networks can take some comfort in the advent of online TV. It also turns out that DVR users are far more likely to watch TV content online than the average TV viewer.

A study by Integrated Media Measurement in San Mateo, Calif., found that 35 percent of people who have a DVR and watched primetime programming in the past month watched four or more episodes of online TV programming, and that's not counting content such as user-created videos on YouTube.

By comparison, only 15 percent of people without the use of DVRs who watched primetime programming in the past month watched four or more episodes of online TV programming.

“This makes sense,” says Amanda Welsh, head of research at IMMI. “Fundamentally, the notion of control of TV viewing has been internalized. Now [in addition to DVRs] there is a second mechanism to do that. That doesn’t mean we’ll give up the first mechanism, it just means the universe is expanding.”

Why should networks take comfort in this? Because online commercials typically cannot be fast-forwarded, meaning viewers have to watch the ads in order to get to the content.

This means the networks are reaching many DVR users with commercials that these viewers may otherwise not see.

“It’s a given that there is a different level of ad viewing in DVR viewing than live viewing,” says Welsh. “Online, the ad experience is very different. This is a mechanism that the DVR audience is embracing and, as of right now, doesn’t have a robust ad-avoidance mechanism.”

In conducting its study, IMMI didn’t rely on people remembering what they watched on DVRs and online, as some other studies have, but used specially programmed cell phones that picked up actual media exposure of the 1,400 panelists involved in the study. “We’re looking at actual behavior. There is no survey,” says Welsh.

The downside of these findings, of course, is that at this point in time online TV viewing is miniscule compared to the amount of time people watch TV programming on TV sets. So for that matter is the amount of time people spend watching time-shifted programming on DVRs

That will change over time, of course, but for now DVRs and online TV are having a small impact on TV viewing.

Nielsen found that 285 million people watched TV in their home in fourth quarter last year for an average 151 hours per month. By comparison, 123 million people watched some type of online video for less than three hours, on average, and just under 74 million people watched time-shifted content an average seven hours.

Meanwhile, the primary reason people use DVRs isn’t to fast-forward through commercials, says Bruce Leichtman, president and principal analyst at Leichtman Research Group in Durham, N.H.

“When we ask people what the most important thing is about DVRs, only 12 percent say skipping ads,” he says. “It’s important to them, but it’s not the most important.”