LOS ANGELES: Advertisers around the world will spend an estimated $5.6bn on YouTube in 2013, a rise of 51.4% on the previous year according to new research, which highlights the growing importance of online video to marketers.

Insights provider eMarketer analysed hundreds of datapoints and studies about YouTube revenues, ad impressions, rates, usage and other factors collected from research firms, investment banks, company reports and interviews with industry executives to develop its figures.

The headline figure referred to gross ad revenues but eMarketer expected that YouTube's net results, after paying partners and content creators, would reveal even stronger growth. It said that $1.96bn net ad revenues for the year was up 65.5% on a year earlier.

That represented a 1.7% share of all global digital ad revenues, which eMarketer noted was higher than the shares of some other major players such as Twitter or AOL.

YouTube's growth is being driven, said the report, by consumers wanting to be able to view video content across the various devices they now own, while parent company Google is also developing products to ensure advertisers can reach this multiscreen audience.

The US alone was anticipated to account for over half of net ad revenues. And most of the total of $1.08bn spent there came from video ads, where YouTube has a significant 20.5% share of the overall US market.

And eMarketer expected that these figures would continue to rise in 2014, to $1.22bn and 21.1% respectively, as the popularity of mobile video increased.

"There's ongoing fragmentation in viewing," Dan Cryan, senior director of digital media with research firm IHS, told the Financial Times. "TV viewing is more or less flat but total video viewing is going up and that's being driven by things like YouTube and Netflix," he added.

The point was reinforced by AOL chief executive Tim Armstrong, who told a UBS media conference that "80% to 90% of internet traffic will be video in the next few years", up from the current figure of around 50%.

Other observers thought YouTube would become Google's biggest revenue driver in the future. Mark Suster of Upfront Ventures, which invests in a large YouTube content partner, suggested to the Wall Street Journal that the video platform could soon be generating $20bn in revenue.

Data sourced from eMarketer, Financial Times, Wall Street Journal, Seeking Alpha; additional content by Warc staff