UK web users spend 240 million hours every month watching videos online, says Experian Htiwise.

According to the Online Video: Bringing Social Media to Life report from the web analytics firm, there were 785 million visits to online video websites in September this year, that's up 36 percent on last year. Google-owned video-sharing site YouTube is responsible for 70 percent of these visits and is the third most popular website in the UK after Google's UK search engine and Facebook.

Furthermore, this equates to 184 million hours spent watching content on YouTube content and the average session lasts for 20 minutes.

Experian Hitwise said the BBC's online catch-up TV service, iPlayer, was the second most popular site for watching video's online, while ITV's equivalent, ITV Player, came third.

"There are now more visits to video websites every month than to email providers, travel or sports sites," said James Murray, marketing research analyst at Experian Hitwise

"The average internet user will make 18 visits to video sites a month and almost half will visit at least three different sites. While YouTube dominates the market, the increase in traffic to video-on-demand and more niche sites demonstrates that content is what matters most to today's internet users and they'll go to whatever site has the content they're most interested in viewing".

When it comes to search topics that drive UK web users to video sites, Music was named the most popular subject, accounting for a third of all search clicks. Experian Hitwise said the majority of these searches were for music videos, and named Lady Gaga as the most searched for artist.

Meanwhile, 17 percent of all search clicks to online video were for TV-related search terms. EastEnders, Britain's Got Talent, X Factor and South Park, all featured highly.