@Integralads found that the percentage of US online video ads that were in-view in Q4 of 2014 was 39.0%, a 9-percentage-point quarter-over-quarter increase. However, this increase in user attention and ad demand has also caused brand risk for video ads as well as the ad fraud rate to slightly increase. In a separate study by Adap.tv, US video buyers said their biggest concerns with video quality inventory were ad viewability and ad fraud (e.g. bots and ad stacking). @eMarketer estimates that US digital video ad spending will increase by 30.4% this year (experienced a 56.0% growth in 2014) to $7.77B. - Link