The latest comScore data reveals that Google sites – primarily driven by YouTube viewings – boast more than 146 million unique monthly video viewers. Content marketers looking to catch an audience among the growing number of online video watchers might be interested in YouTube's most-searched for queries for 2010.

According to the YouTube blog, top monthly video searches throughout 2010 varied from hard news topics to tech developments, and from celebrity sensations to sporting events. The consistent thread among the top searches is that they reveal consumers look for timely video content.

In January, concerned consumers were searching for YouTube videos to learn more about the disaster in "Haiti."In April, the online video community was buzzing about Apple's release of the "iPad." YouTube officials say the top search terms "reveal the interests, issues and entertainment that connected" Americans in 2010.

Marketers looking to connect with online video viewers should remember that they must optimize their video descriptions to catch clicks among searchers. As Brafton has reported, YouTube's Topics on Search feature rewards brands for practicing video SEO.