Google Inc. (NASDAQ: GOOGL), by far the Internet’s largest search engine, also attracts the more video viewers to its various websites, including YouTube, than any other content property. In the month of August, Google sites attracted more than 168 million unique viewers in the United States, nearly double the total posted by second-place finisher Facebook Inc. (NASDAQ: FB). The total number of unique U.S. viewers reached about 191.5 million, down slightly from 192.11 million posted in July. More than half of all Americans watched a video from a Google site in August.

The remaining sites in the online video viewer rankings, according to comScore, are:

2. Facebook: 88.94 million unique viewers
3. Yahoo! Inc. (NASDAQ: YHOO) sites: 48.30 million
4. IAC/Interactive Corp.’s (NASDAQ: IACI) Vimeo: 43.22 million
5. VEVO: 42.96 million
6. Maker Studios, from Walt Disney Co. (NYSE: DIS): 37.86 million
7. Fullscreen – 35.08 million
8. Microsoft Corp. (NASDAQ: MSFT) sites: 33.25 million
9. Comcast Corp. (NYSE: CMCSA): 32.45 million
10. Turner Digital: 31.49 million

comScore also measures advertising reach; that is, the percentage of the U.S. population that is served an ad by a given advertising platform. The leader here is ad exchange BrightRoll with a reach of 36.7% of the U.S. population. Google ranked second with a reach of 30.6% and AOL, now part of Verizon Communications Inc. (NYSE: VZ), ranked third with 27.3% reach.

comScore also released its August list of the top 50 multiplatform Web properties. The research firm said that 259.2 million unique U.S. desktop and mobile device users visited a Web page in August. Google’s various sites attracted 245.4 million unique viewers, and Facebook attracted 217.8 million. Yahoo, Amazon.com Inc. (NASDAQ: AMZN) and Microsoft rounded out the top five.

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