“Lost” and “SNL” are also popular online.

Lost, Saturday Night Live and Grey’s Anatomy were December’s three most popular entertainment TV programs streamed from tagged network websites and embedded network video players, according to VideoCensus data from Nielsen Online (via MarketingCharts).

In its first public release of ratings for online individual TV programs, Nielsen reported that ABC.com’s Lost had 1.4 million unique viewers in December — the most among streamed online broadcast TV network entertainment programs. 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 websites included were from broadcast networks that had tagged their online offerings: ABC.com, CBS Television, CWTV.com, FOX Broadcasting, and NBC.com. The rankings exclude Hulu, which currently does not report VideoCensus data at the program level.Rankings include 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, VP 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 TV, 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. These viewers are driven by a morning-after water-cooler effect.”

Nielson’s reports are incomplete until they start including numbers from Hulu as well, and we also need information about how these numbers stack up against popular online video sites.

It would have been interesting to see numbers from Novemeber and October, as “SNL” surely led the way with its political coverage.