Molto this is a competely different thing altogether than power of myth, it came out around the time of episode one; The phantom menace and was only aired once I believe on bbc2.
the power of myth dvd is phenomenal quality over those old vhs tapes. Speaking of campbell there is also a memorial piece called the hero's journey and has Lucas on it .
PBS also has many, many more hours of interview material done for power of myth but it has never been shown on a t.v. broadcast or even been released on home video.
there are bits and pieces of these extra conversions between moyers and campbell in the book the power of myth by bill moyers.
the power of myth would not have seen the light of day if it was not for george lucas. He let them film it at skywalker ranch, and even help pitch it to PBS and donated funding. almost similar to the way he helped another one of his mentor's kurosawa in getting kagemusha funded and filmed .
the mythology of star wars with bill moyers and george lucas almost is an apocryphal volume to the power of myth.