Internet users will begin to see a new form of advertising on web pages this week, following the UK launch of a system that embeds video adverts within the text of articles.

Sites subscribing to the service will highlight certain keywords, which launch an advertiser’s video when hovered over with the mouse cursor. Readers can turn off the video by moving the mouse away, or choose to visit the advertiser’s website by clicking on the video or accompanying text.

The system was developed by Vibrant Media, which created IntelliTXT, a text-based keyword advertising service. It differs from Google’s contextual advertising products by embedding the adverts within the content of articles rather than placing them around the edge of text or on search results pages.

"We’re bringing advertisers into the content," Anna Kassoway, the company’s vice president of marketing, said. "Advertisers feel that this is one way that they can cut through the noise that’s out there."

As the people who make up the young, affluent demographic often targeted by marketing have begun to spend less time reading newspapers and watching television, advertisers have followed their audience on to the internet and diverted increasing proportions of their budgets into online campaigns.

Traditional advertising budgets still dwarf the online market, but many companies now use internet marketing to back up offline campaigns. Web-based advertising can reach a more focused audience than TV or radio – for example, users of a music download service are prime targets for record labels as they are interested in music and poised to make a purchase.

Web advertising also provides more accountability. Companies can see how many people are viewing their adverts and monitor the proportion that goes on to view their website and make a purchase.

"If successful, the mixture of targeting and accountability, along with the visual impact and flexibility of video is sure to be a powerful tool for some advertisers," the marketing consultants Web Search Workshop stated in a recent report on the online advertising market.

"Products which can sell visually, like property, hotels or any physical products will be able to make more of an impact on its audience."

Vibrant Media said that film companies and computer game producers have been among the most enthusiastic users of video adverts in the US, where the system has been in use for three months.

"Gamers are an insanely difficult audience to impress," Paul Caparotta, advertising manager with games company Ubisoft, said. "They are inundated with marketing messages and expect their online experience to be visually immersive."

Vibrant Media's chief executive, Doug Stevenson, said that successful adverts have to attract viewers with quality content, rather than treating web users as a captive audience.

"Movie trailers work very well because the user feels really involved," he said. "We’re trying to make ads much more visual for the user, because if you make ads work for the user, you make them work for the advertiser too."

Explore Tech & Web

• Personal Tech

• The Web

• Gadgets & Gaming