Advertising has overtaken paid-for content as the key generator of online TV revenues, fuelled by growth in commercial video-on-demand.

Figures from Screen Digest, analysed in Ofcom’s Communications Market Report, show that free-to-view web TV content accounted for £54.3m in revenues in 2009 - 57.7% of the sector’s total of £94m. The remainder came from paid-for content.

The figure is more than double the £24.3m in revenues from online ads in 2008, which represented 44% of that year’s £54.8m total.

The report also reveals that US site Hulu, which is co-owned by Disney, NBC Universal and News Corp, had a unique audience of 100,000 people in the UK in the year to May 2010, even though it is not legitimately available here.

Blinkbox was the fastest growing of the non-broadcaster web platforms last year, tripling its unique audience to 384,000 users.

It currently has almost twice the audience of SeeSaw, which had 200,000 users four months after its launch.

Over roughly the same period (the year to April 2010), iPlayer requests to view almost doubled, from 53 million to 93 million. Live streaming now accounts for 8% of iPlayer viewing.

The BBC service is also now used by 17% of active internet users, more than four times the reach of Channel 4’s 4oD (3.6%) and ITV Player (3.4%).