ComScore recently released the latest installment of its monthly US Online Video Rankings and there is at least one big item of note within the May 2012 numbers.

Americans viewed an all-time high of 10.076 billion online video ads during the 31 days of the month. Hulu was the highest contributor to the 11-figure metric, with more than 1.666 billion video ads delivered, while Google/YouTube came in at a not-so-distant second place on the monthly Top 10 Video Ad Properties by Video Ads Viewed charts with 1.385 billion ads served. Brightroll also broke into the Billion Ads Served club to round out the top three spots, delivering 1.130 billion ads during the entirety of May.

What’s even more impressive about those 10.076 billion online video ads served is the overall number of Americans who watched online videos dipped slightly from April to May, as did the total number of online videos consumed.

180,785,000 individuals living in the US watched online video in April, compared to the 180,503,000 individuals who watched in May. That’s a drop of roughly 0.2%. Similarly, individuals in the US consumed 36,848,001,000 online videos in April, compared to 36,556,792,000 online videos in May. That’s a decrease of roughly 0.8% month-over-month.

Meanwhile, the number of online video ads served from April to May went up from 9,478,975,000 to 10,075,499,000. That’s roughly a 6% increase in the number of video ads served month-over-month, a 7% increase in the frequency of online video ads served per video, and great news for anyone involved in the online video ad industry.

Check out all the latest fun facts and figures from comScore’s May 2012 US Online Video Rankings here.

Amazing vintage kitty cat watching YouTube image by Still Burning.