Until now, the worst thing about video-sharing website YouTube has long been the inane comments that are so bad they're almost reason enough to avoid the site. To that we can now add extra advertising, thanks to owner Google's decision to overlay commercials on the videos themselves.

Starting this week, video clips from the 1,000-plus YouTube content partners may feature advertising on the bottom fifth of the screen similar to tickers on television news shows or promotions sometimes used during other broadcasts.

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The overlays appear 15 seconds into a clip and last for 10 seconds, during which time they can either be ignored or - as Google hopes - clicked on. Clicking pauses the video and initiates a full-size commercial instead, after which, the original video resumes.

Advertising is initially limited to content partners to avoid paid-for commercials appearing on unlicensed videos or content on which advertisers would not wish to see their products. This should avoid issues similar to the BNP row that has caused problems for Facebook.

With an eye on the £2 billion such video advertising is projected to be worth by 2011, Google will clearly be banking on YouTube users not being turned off by the adverts. Now, if only they could do something about those comments.