Most people think their PC is the must-have communications device, with TV (not surprisingly - since it's an entertainment device) pretty far back in second place, but online video is not yet a significant part of the PC experience (not surprisingly, since it's primarily a communications device), according to a new study.

Watching online video ranks merely seventh among users' primary PC activities, writes AdWeek, citing a survey sponsored by the Cabletelevision Advertising Bureau (CAB) and conducted by Frank N. Magid Associates. The study of consumers age 12-54 found that TV ads as long as 42 seconds were tolerable to watchers, but on PCs and laptops tolerance is less - 18 seconds - and nine seconds for cell phones.

More than 60 percent said they prefer watching video on TV rather than a computer or iPod. Only 12 percent of those with video-enabled phones said they used it for video. Only 30 percent said they had and additional screen device (beyond a TV and computer) used for watching video.

The bottom line, according to CAB president Sean Cunningham, is that "screens are not interchangeable, video is not interchangeable and advertising is not interchangeable," from one device to another.