Pat O'Brien, the co-host of The Insider, whose frequent bouts with alcoholism has made him the kind of celebrity that the show itself covers nightly, has been demoted to a Los Angeles-based correspondent, with Lara Spencer taking over officially as the show's sole anchor, CBS announced Friday. O'Brien returned to rehab last February. Spencer, who has co-anchored The Insider from New York, will move to California as part of a longterm pact, executive producer Linda Bell Blue said in a statement. Blue included her announcement of the anchor change in a statement announcing the conversion of the show's production facilities to high definition. "We are once again making history by being the first entertainment newsmagazines to move into HD. Lara is essential to the exciting future of the show," Bell Blue said.