ComScore’s latest Video Metrix numbers from July show that Facebook has climbed to third in the U.S. with 46.6 million unique video viewers, up 5.3 million from June. Facebook landed at number 3 right behind Google (YouTube) in first place with 143.2 million unique viewers and Yahoo with 55.1 million viewers.

In June, Facebook had 41.3 million unique U.S. viewers, according to ComScore, even as the company reported that same month that more than 20 million videos are uploaded monthly generating 2 billion video views during the same period around the world.

Overall ComScore reported that 178 million U.S. users — 84.9% of the Internet audience — watched videos online during the month of July for an average of 14.7 hours each. Google had the lion’s share of these viewers, 143.2 million with 1.8 billion viewing sessions for an average of 283 minutes (4.7 hours). Yahoo had around 55 million viewers with 238.3 million sessions averaging about 29 minutes while Facebook had over 166 million viewing sessions for its 46.6 uniques for an average of 18.3 minutes a pop.

The rest of the top ten list included, in order: Microsoft, VEVO, Fox Interactive Media, Turner Network, Viacom Digital, Disney Online and Hulu. Despite being lower on the list for unique viewers, several of these companies generated more and longer viewing sessions than Facebook. For example, Microsoft in fourth place had 219 million sessions averaging 40 minutes and VEVO had 202 million averaging 69 minutes.

Another interesting tidbit from ComScore this month is that the amount of time watching ads online is on the rise. Video ads averaging 24 seconds (.4 minutes) account for 9.8% of videos viewed and .9% of all minutes spent viewing online videos.