• by Mark Walsh  @markfwal, July 15, 2011

Video advertising continued to grow last month in tandem with the expansion of the online video audience. Americans watched 5.3 billion video ads last month, up from 4.6 billion in May, according to the latest data from comScore. Video ads also made up a larger share of all videos viewed: 13.6% compared to 12.6% in May. As a proportion of time spent, ad viewing increased slightly to 1.3% from 1.2% of all minutes watched.

Among video ad networks, Hulu was again tops with more than 1 billion ad impressions in June, followed by Tremor Media, with 753 million, Adap.tv, 677.7 billion, and BrightRoll, 628.6 million. Hulu's total, however, dropped by about 300,000 video ads from May, while Tremor and BrightRoll added about 53,000 and 63,000 ads, respectively.

Time spent watching video ads totaled more than 2.2 billion in June, with Tremor pushing ahead of Hulu to deliver the highest duration of video ads at 429 million minutes. Hulu dipped to 424 minutes from 560 in May. Since broadcast and cable TV shows generate most of the viewing on Hulu, the season's end for many TV series in May likely accounts for some of the drop-off.

Video ads reached nearly half (49%) of the total U.S. population an average of 35.6 times during the month. Hulu delivered the highest frequency of video ads to its viewers with an average of 38.8. The top video ad networks in terms of their reach of the overall population were: Tremor Media at 44.3%, BrightRoll at 38.5%, and Break Media at 37.6%.

ComScore data reflects only streaming-video advertising and does not include other types of video monetization, including overlays, branded players or matching banner ads. 

Looking at overall video consumption, the total number of viewing sessions cracked the 6 billion mark for the first time, rising to 6.2 billion in June from 5.6 billion in May. The number of people watching video increased by 2 million to 178 million, or 85.6% of the U.S. Internet population.

The average time spent watching Web video also increased, to 16.8 hours from 15.9 hours. YouTube drove the biggest share of that activity, with 149 million unique visitors racking up 2.3 billion viewing sessions. Users spent an average of 5.4 hours on the Google-owned video hub.

Music video site VEVO was second to YouTube in audience with 63 million viewers, followed by Yahoo (52.7 million) Microsoft (50.7 million), and Viacom Digital (49.5 million). Facebook fell a spot to sixth place, with 47.7 million video viewers, while Amazon broke into the top 10 in June, with a video audience of 23.3 million.