As the Web video ad industry grows, so do the number of questions about the legitimacy of some of the available ad inventory out there. Such questions as: Where are my ads running? And how do I know if anyone can actually see them?To head off such queries before doubt solidifies, a group of companies in the video ad sector formed a consortium aimed at establishing a common standard for measuring Web video viewability, dubbed OpenVV (Open Video View). The idea is get all the players on the same page when it comes to criteria for defining whether a video ad can actually be seen. And hopefully, the result is that brands get more comfortable—and dollars flow to the medium.The group includes such frenemies as TubeMogul (which built the tech), BrightRoll, Innovid, SpotXchange and LiveRail (and notably doesn’t include YouTube, Hulu, AOL, Yahoo or the rest of the NewFront crew). That’s because DSPs like TubeMogul, SSPs like LiveRail or ad networks/exchanges like BrightRoll run ads all over the Internet, and thus face the most questions about ad viewability.