Accurate monitoring of online video consumption across multiple platforms is not an easy task. But for publishers and advertisers hoping to make a business of this, complete metrics is essential.  Nielsen Online is developing new system to track online video consumption on multiple sites by identifying the distinct "audio signature file" which is specific to particular shows. Last month, I spoke with Jon Gibs, VP of Media Analytics at Nielsen Online about future developments in online video metrics. — Andy Plesser, Executive Producer