Updated

Videos of celebrity has-beens using illegal drugs or simulating drug use are circulating on the Internet in clips apparently taken from a forthcoming VH1 show about fallen stars in rehab.

In one segment, "Taxi" actor Jeff Conaway simulates snorting cocaine. Another shows a man "free-basing" cocaine — or pretending to.

"By the way, this is pablum," Conaway says as he inhales. "I don't want you to get the wrong idea."

Click here to see the free-basing video.

Click here to see the Conaway video.

“Celebrity Rehab,” scheduled to premiere Jan. 10, will track celebrities gone bad as they go through treatment for drug and alcohol addiction.

Among the nine former stars expected to be featured are “American Idol” finalist Jessica Sierra, porn star and onetime California governor hopeful Mary Carey, actor Daniel Baldwin, actress Brigitte Nielsen and former pro wrestler Chyna, according to The New York Post.

A spokeswoman from VH1 refused to confirm the names of the participants, other than Sierra, the Post reported.

Dr. Drew Pinsky will host the show; filming is under way in Pasadena, Calif.

Sierra, a 2005 "Idol" finalist, was arrested in April for striking someone in a Tampa, Fla., bar with a glass. She pleaded no contest last week to battery and drug charges for cocaine possession at the time of the incident, and was sentenced to 12 months probation.