I don't remember these promos but I do remember watching Mork and Mindy around that time. I came across it after searching for a late 1970s Robin Williams standup performance where he is completely coked up and is joined on stage by John Ritter who was sitting in the front row with Henry Winkler. Ritter and Williams go on to do some improve, with both sweating furiously.
Here it is. Ritter comes on in the second half. Henry Winkler is in the audience and supposedly Tony Danza as well although I haven't seen the whole thing.
AMERICAN FREE PRESS Roving Editor Mark Anderson welcomes E. Michael Jones to the May 20 show, to outline his new book on capitalism and why this widely revered economic system is not really freedom's friend.