YouTube, the largest video-sharing Website, has started to run full-length TV shows from CBS Corp’s archive, in its latest step to boost advertising revenue by adding professional programing.

The site, owned by Google Inc, said on Friday it was talking to other TV networks to sign similar deals to CBS. Many TV networks already run short clips on YouTube, which also offers millions of home videos uploaded by users.

A mix of archive CBS shows, including “Star Trek,” “Young and the Restless” and “Beverly Hills 90210,” will now be available in full-length episodes of 20 minutes to 48 minutes.