A new currency in video advertising is the viewable impression — something that's top of mind for advertisers and publishers. According to the Media Rating Council and IAB standard a viewable video impression occurs when at least 50% of an ad's pixels are visible on a screen for at least two consecutive seconds.
So what affects whether an ad is viewable? Our Active View research uncovered the Five Factors of Video Viewability - summarised below:

November 2015
  • YouTube is 1.7x more viewable than the rest of the web: In the UK the average viewability of video ads across the web (not including YouTube is 58%), whilst on YouTube it is 91%
  • Mobile first: Video ads are significantly more viewable on mobile and tablet than on desktop. For YouTube, where over half of views come from mobile devices, we found the same - viewability on mobile and tablet was 94%
  • Non viewability is driven by ads being on the background tab or off screen, as well as being scrolled past or abandoned within two seconds
  • Player size matters: large players on video-focused sites demonstrate significantly higher viewability
  • Location, Location, Location: horizontal and vertical positioning on the page correlate to viewability, top centre of the page is optimal

For more detail please take a look at the full research report.