http://www.comscore.com/press/release.asp?press=1529

...nearly 75 percent of U.S. Internet users watched an average of 158 minutes of online video per user during the month. Google Sites topped the monthly rankings with both the most unique video streamers and most videos streamed.

  

Google Tops U.S. Online Video Rankings

May saw Americans view more than 8.3 billion video streams online, and Google Sites once again ranked as the top U.S. streaming video property with 1.8 billion videos streamed (21.5 percent share of streams), 1.7 billion of which occurred at YouTube.com. Fox Interactive Media ranked second with 680 million streams (8.1 percent), followed by Yahoo! Sites with 387 million (4.6 percent) and Viacom Digital with 237 million (2.8 percent).