Dr. Frasier Crane, "Celebrity Rehab" host? It's not that far-fetched. This video sheds some Hollywood spotlight behind the scenes of "Frasier," that ninetiest of all '90s sitcoms, and finds that the fake radio doc's callers were largely celebrities making "The Simpsons"-style guest appearances. Helen Mirren, Halle Berry, Matthew Broderick, Ben Stiller and even a young Hilary Duff brought their problems to the "airwaves" in uncredited roles. When you hear them now, it's pretty obvious, and pretty awesome.