CBS Corp. said that it is buying the Los Angeles-based online video guide Clicker Media Inc. and will make the company’s co-founder president of its CBS Interactive unit, headquartered in San Francisco.

Clicker.com is used to find legally posted TV shows, movies and videos on the Internet. It has about 2.5 million users per month and indexes more than 1 million TV shows alone, CBS said in the Friday announcement.

Jim Lanzone, who is Clicker’s chief executive, will replace Neil Ashe, who announced in December that he planned to leave CBS Interactive. Prior to founding Clicker in October 2008, Lanzone was the chief executive of Ask.com.

Clicker is “one of the leading navigation and discovery tools for video programming on the Internet,” said CBS Chief Executive Leslie Moonves in a statement. “If we can help grow Clicker to its full potential in the years ahead, the strategic value could be tremendous.”

Clicker has received roughly $21 million from investors that included Benchmark Capital, Jafco, and Redpoint Ventures. Terms of the sale to CBS were not disclosed.

CBS Interactive includes online sites for its various television properties, the CNET.com tech site and the Gamespot.com multiplayer game site. Lanzone will be based at CBS’s San Francisco office.

It was not disclosed whether the entire Clicker operation also will move to the Bay Area.