Mobile devices already account for the majority of online video consumption at 61%, but mobile is set to grow its share further in coming years. In fact, it will power the next phase of online video viewing according to Publicis-owned media agency Zenith. In the third -- and most recent -- edition of the agency's Online Video Forecasts, it predicts that time spent viewing all online video will increase 20% in 2017.The study contains historical data and forecasts of online video consumption and advertising. It analyzes 63 key markets around the world, and includes all video services distributed via the Internet.It's worth noting that this study does not include pay-TV services delivered via a private network, such as broadcast, cable, satellite or telco. These estimates are for Internet video consumption only.The study found that consumers worldwide will spend 47.4 minutes a day viewing online video this year, largely driven by a 35% increase in mobile video consumption. Zenith predicts that fixed-device video consumption will reach its peak in 2017, and start to decline in coming years -- by 1% in 2018 and 2% in 2019. The agency acknowledges that viewing on smart TVs is growing, but it's not compensating for the declines in desktop and laptop viewing as consumers shift to mobile devices.Mobile video viewing is expected to grow 25% in 2018 and 29% in 2019, as mobile device penetration grows, screen/display quality improves further and mobile networks evolve to offer faster connectivity. By 2019, Zenith claims mobile devices will account for nearly three quarters of all online video viewing.Overall online video consumption is also growing rapidly, particularly on social platforms which have added new tools to encourage creation and sharing of videos, including the live streaming of sporting and other events. According to Zenith's estimates, Facebook is already the second-largest supplier of video in many markets (after YouTube).Zenith also estimates that spending on advertising is set to grow, as online video gains more eyeballs. The agency forecasts global online video advertising expenditure will grow 23% in 2017 to $27.2 billion, up from $22.2 billion in 2016. It will reach $38.7 billion in 2019.The agency also expects mobile advertising will gain a greater share of advertising revenue, pointing out that, even though mobile gets more video viewing time, advertising spend on fixed video will be $15.2 billion this year, compared with mobile video ad spend at $12 billion. But in 2018, mobile will overtake fixed, and generate $18 billion in advertising revenue as advertisers follow eyeballs to mobile.While Zenith doesn't explicitly say so, it seems likely the big winners in terms of advertising dollars will be the social networks that embrace video, such as Facebook and Snapchat. The type of video they are offering seems to fit in well with mobile consumption, and consumers are already spending a lot of time engaged with these networks.At the same time, there may be a surprise lurking in the form of smart TVs and connected set-top boxes beyond 2019. Even as consumers continue to cut the cord, the actual TV set continues to be an important part of most households. And newer TV sets tend to have Internet connectivity built in. So there's going to be a steady stream of new smart TVs entering consumer homes, and rapidly growing penetration of OTT services such as Netflix and Amazon. That could shift video consumption back to the fixed TV, and compete with mobile devices for user time -- at least for some forms of video content, for some segments of the population.Still, even though the market space remains very much in flux, the study is clear that online video consumption is growing, and mobile video is going to be one of the most important areas for digital advertising.— Aditya Kishore, Practice Leader, Video Transformation, Telco Transformation