While Google's YouTube remains the most popular video sharing site in the U.S., Facebook is now the second most popular place to watch videos online. According to the latest data from comScore, Facebook just took the #2 spot from Yahoo and continues to grow rapidly. While Facebook.com served 166 million viewing sessions in July, this number was up to 243 million in August.

In contrast to Google's video properties, though, where the average user spent close to 270 minutes in August, Facebook's users are far less engaged and only watched 21 minutes. Traffic to YouTube continues to grow - though at a relatively slow pace - it's worth noting that the time the average user spent on the site last month was actually down slightly (282.7 in July vs. 269.5 in August).

The newest entry in comScore's top 10 last month was the Break Media Network, which is home to sits like Break.com, Screen Junkies and Holy Taco. In total, Break Media reached 42 million viewers last month. The network also featured in comScore's top 10 for June. Back then, the site only saw 26 million unique viewers for the month. Hulu fell out of comScore's top 10 this month.