YouTube passed the 100m viewers mark in January, according to online researcher ComScore.
The research firm said that overall, Americans viewed 14.8 billion online videos in January, which is a 4 percent jump from December. And YouTube had the lion's share of that increase, accounting for 91 percent of the growth.
ComScore also noted that more than 147 million US internet users watched an average of 101 videos each in January. And the average viewer watched about six hours worth of them in January.
Google, which owns YouTube, was listed as the top US video property with 6.4 billion videos viewed. That accounts for 43 percent of the online video market share. And YouTube.com made up about 99 percent percent of all videos viewed at on Google properties. Fox Interactive Media came in a distant second with 552 million videos viewed, or 3.7 percent, followed by Yahoo Sites with 374 million or 2.5 percent.