[math-fun] Mandelbrot's Conjecture (as mentioned in this video interview)

In this interview: http://bigthink.com/benoitmandelbrot He mentions two forms for the Mandelbrot that are believed to be equivalent but are not proved to be so. He doesn't give the details - can anyone either explain in more detail or point me at the details ? I've tried looking on the web but failed to find the conjecture the he mentions... bye Dave