Boston-based Visible Measures, a startup specializing in measuring internet video, has raised a $13.5 million second round led by Mohr Davidow Ventures, with participation from previous backer General Catalyst Partners. The company raised $5 million from General Catalyst in early 2007, bringing its total raise to $18.5 million. The company tracks online video, helping publishers and advertisers get better data. To that end, it also announced the acquisition of Vidmeter, which also helps manage and monitor syndicated online video, with a focus on viral, user-generated content. Visible Measures will integrate Vidmeter’s technology in the first half of the year. The funding round will go towards funding expansion. Release.