Puzzler: Mos Def

So last time I asked you folks where one might see the venerable Steve Cropper in a Jack Black film. The more perceptive amongst you might know that the answer was in a scene from Be Kind Rewind,  starring Mr. Black and the wonderful Mos Def as two hapless video-store clerks whose entire library gets wiped clean in some sort of freak magnetic happening, and they then decide to re-film the entire library themselves. Much hilarity ensues. Steve Cropper is to be found sitting alongside Booker T. Jones on a train, portraying themselves as fans of Fats Waller. Unfortunately there appear to be no clips of this brief cameo anywhere on the Intertubes.

So the next question...?

Which rocker has Mos Def portrayed on the big screen, and in which movie?