Google has launched an advertising service that allows businesses to show videos online. An example can be seen on the Google Video Ads demo page.

The service only plays videos when a user clicks the 'play' button, which Google said is designed to protect the user experience and provide advertisers with genuine leads.

To simplify the process, once an advert of up to two minutes long has been uploaded by a company its management is handed over to Google.

Advertisers can then buy space on specific sites or spread the ads around related sites based on the context of the material.

Google said that the video ads will compete in the advertising auction with other text, image and Flash ads for placement on a site. Adverts are paid for on either a cost-per-impression or cost-per-click basis.

Advertisers can measure the effectiveness of their video ads by tracking play-back rates and click-throughs to their destination site, as well as how long users interact with the video.

Paramount Studios, which has already trialled the service on specific sites, claimed that it was happy with the results.

"Pull marketing (getting people to click to play relevant content) is much more effective than push marketing or auto-play ads," said Andrew Lin, vice president of interactive marketing at Paramount Vantage.

"I could not ask for better placement. Paramount was able to choose where the video trailer played, and it was on sites that were highly relevant to our target audiences."

The worldwide Google service offers adverts in Japanese, simplified Chinese, Danish, Korean, Dutch, Norwegian, English, Polish, Finnish, Portuguese, French, Russian, German, Spanish, Hungarian, Swedish, Italian and Turkish.