At the end of every episode of Mork & Mindy, the alien visitor Mork calls his boss Orson to give a report. The show depicts the call by having Mork chant, "Mork calling Orson. Come in, Orson!" as the camera zooms in on his face. Soon this shot dissolves into a bundle of vivid colours which shimmers and undulates. The object is semi-transparent, making it appear three-dimensional.
The following animated GIF, produced from this YouTube clip, gives some idea of the effect, though neither of these match the quality of the DVD:
Given that the show premiered in 1978, I assume that this effect was produced with analogue equipment. How exactly was it done (or if nobody knows for sure, how might it have been done)?