The British Broadcasting Corp. began showing excerpts from its news and entertainment programs on the YouTube video-sharing Web site Friday, becoming the first international broadcaster to ink a major deal with the Google Inc.-owned portal.

In an agreement that analysts described as a key step for both the BBC and YouTube, the British broadcaster is offering three branded channels on the site, including one showing up to 30 news clips a day. The deal gives the BBC access to millions more viewers and gives YouTube the credibility of the venerable British broadcaster.