Viewability has emerged as one of the hottest topics in the online video industry this year, for good reason - video ads that aren't seen diminish the advertiser's ROI and undermine the integrity of the market.

However, the industry is addressing viewability and at the recent Video Ad Summit, IAB presented a session that dug into the details. Participants included Rob Brett (Viacom), Tal Chalozin (Innovid), David Gunzerath (MRC) and Julian Zilberbrand (Zenith Optimedia) with Matt Prohaska moderating.