• by Gavin O'Malley  @mp_gavin, February 13, 2009

ABC.com's popular series "Lost" had 1.4 million unique viewers in December--the most among online broadcast TV network entertainment programs streamed from tagged network Web sites and embedded network video players, according to new data from Nielsen Online. 

NBC.com's "Saturday Night Live" was a close second, with 1.1 million unique viewers, followed by ABC.com's "Grey's Anatomy" with 879,000 unique viewers in December.

The network Web sites included were from broadcast networks that had tagged their online offerings: ABC.com, CBS Television, CWTV.com, FOX Broadcasting and NBC.com.

Notably, the rankings exclude Hulu (which currently does not report VideoCensus data at the program level) and included unique viewers who viewed a full episode, part of an episode or a program clip during the month.

"As I see it, the broad diversity of top television network entertainment programs online suggests that there is more to online viewership than a simple extension of the TV audience," said Jon Gibs, vice president of media analytics, Nielsen Online. "While the online popularity of some shows like 'Grey's Anatomy' suggests that some people are using the Internet to catch up on programs they usually watch on television, the online popularity of other programs like 'Saturday Night Live' indicates that there is a Web audience that might otherwise not watch these programs at all."

When ranked by time spent per viewer in December,CWTV.com's "Privileged" ranked first, with 215 minutes per viewer, followed by NBC.com's "Chuck" and "Lipstick Jungle," with 163 minutes and 153 minutes, respectively.

"Audience size is clearly important, but we are still in a 'taste testing' phase for online long-form video," said Gibs. "Consumers are starting a stream to see if they like it, and maybe they finish watching the program and maybe they don't. Advertisers should be looking to balance overall reach with minutes per viewer, since those programs with longer viewing times are ones where consumers are much more likely to actually watch the advertising."

Separately, a new report from research firm Knowledge Networks has found that one in five--or 21%--of Web users ages 13-54 now access streaming video to watch full episodes of TV programs. That percentage is up from just 10% in 2006.

In addition, the report shows that among ages 13-54 streamers of TV network content, use of third-party hosting sites like Hulu has doubled since 2007, from 14% to 28%.

The networks' own Web sites are still streamers' most common source of network content. A full 87% say they view full TV programs online so that they can "watch a current episode that I missed"--more than double the proportion--40%--who are watching "older" or "last season" episodes.

Making full TV episodes available online also creates goodwill for networks and sponsors alike, according to Knowledge Networks. A total of 86% of age 13-54 streamers said they are more engaged with programs that they can watch on the Internet--up from 78% in 2006.

And 66% said that having access to complete episodes increases their consideration of sponsoring brands, compared to 58% in 2006.