Almost half (46 per cent) of video ads served across the Internet -- excluding YouTube -- in the United States will never be seen by consumers, according to a study by Google. This figure drops to 42 percent in the UK. The findings come as advertisers continue to grapple with issues arising from viewability -- where an ad is served on a page to how quickly it disappears when a user scrolls -- and as Google continues to encourage advertisers to consider its TrueView formats following a significant investment since its launch in 2010.