Google sites have topped the online video content property with 145.8 million unique viewers in the US, primarily driven by video viewing at YouTube.com.

Yahoo! sites stood second with 61.8 million viewers, followed by VEVO with 50.3 million viewers in the month of Novermber 2010.

AOL, which acquired 5min in September, secured fourth place with 47.7 million viewers and Viacom Digital had 47.3 million viewers.

According to the report, Google sites had the highest number of viewing sessions with nearly 2.0 billion, and average time spent per viewer at 271 minutes, or 4.5 hours.

Americans viewed more than 5.4 billion video ads in November, with Hulu generating the highest number of video ad impressions at more than 1.1 billion.

Tremor Media Video Network ranked second overall (and highest among video ad networks) with 477 million ad views, followed by ADAP.TV (446 million) and Microsoft Sites (427 million).

Video ads reached 49% of the total US population an average of 36.8 times during the month, and CWTV.com delivered the highest frequency of video ads to its viewers with an average of 68.5 over the course of the month after recently starting to run full ad-loads comparable to those of television.

The report revealed that 84.2% of the US Internet audience viewed online video, and the duration of the average online content video was 5.1 minutes, while the average online video ad was 0.4 minutes.

Further, video ads accounted for 15.3% of all videos viewed and 1.4% of all minutes spent viewing video online.