While Google and YouTube continue to rule video advertising, a group of properties have come to underpin the broader marketplace. Indeed, each of the top five video ad properties, including BrightRoll, Hulu, Adap.tv, and TubeMogul, as well as YouTube, delivered more than 1 billion video ads last month, according to the new data from comScore. Following Google’s prized property -- which ranked first with 1.41 billion ads -- the BrightRoll Video Network accounted for nearly 1.39 billion ads; Hulu was responsible for 1.33 billion ads; Adap.tv chalked up 1.15 billion ads; while the TubeMogul Video Ad Platform recorded 1.04 billion ads. Continuing to break records, more than 180 million U.S. Web users viewed 33 billion pieces of video content -- and 11 billion ads -- in June, according to comScore. Driven primarily by video viewing at YouTube.com, Google sites ranked as the top online video content property in June with 154 million unique viewers, followed by Yahoo Sites with 51 million, Facebook.com with 49 million, VEVO with 46 million and Viacom Digital with 39 million. Last month, time spent watching video ads totaled 4.6 billion minutes, with BrightRoll Video Network delivering the highest duration of video ads at 805 million minutes. Overall, video ads reached 53% of the total U.S. population an average of 68 times during the month. Hulu, for its part, delivered the highest frequency of video ads to its viewers with an average of 52, while ESPN delivered an average of 34 ads per viewer. Looking specifically at YouTube’s partners, video music channel Vevo attracted 45.1 million viewers, while Warner Music drew 26.1 million viewers. Trailing both, gaming channel Machinima ranked third with 23.6 million viewers, followed by Maker Studios with 21.2 million and FullScreen with 16.2 million. Among the top 10 YouTube partners, Machinima demonstrated the highest engagement -- 76 minutes per viewer -- followed by Vevo -- 50 minutes per viewer. Among all YouTube partners, Vevo streamed the most videos -- 567 million -- followed by Machinima -- 447 million.