Published: 16.03 Europe/London, June 17, 2011

Google sites, driven primarily by video viewing at, ranked as the top online video content property in May with 147.2 million unique viewers, according to research by comScore. 176 million US internet users watched online video content in May for an average of 15.9 hours per viewer.

The total US internet audience engaged in more than 5.6 billion viewing sessions during the course of the month.

Runner-up of the best watched US video sites is Vevo with 60.4 million viewers, followed by Yahoo! sites with 55.5 million viewers. came in fourth with 48.2 million viewers, while Viacom Digital ranked fifth with 46.5 million viewers.

Google sites had the highest number of viewing sessions with more than 2.1 billion, and highest time spent per viewer at 311 minutes, crossing the 5-hour mark for the first time.