Reston, Va.—Underscoring the mainstreaming of online video as a potentially powerful marketing tool, digital marketing company comScore reported that individual viewings of online videos in the U.S. totaled 12.7 billion during November, a 34% increase over the same month in 2007.

Google sites ranked as the top U.S. video property with nearly 5.1 billion videos viewed, representing a 40% share of all videos viewed. The YouTube.com video-sharing site accounted for more than 98% of Google’s total.

Fox Interactive Media ranked second with 439 million videos (3.5%), followed by Viacom Digital with 325 million (2.6%) and Yahoo sites with 304 million (2.4%).

More than 146 million U.S. Internet users watched an average of 87 videos per viewer in November, according to comScore.

—Christopher Hosford