search for episode title "choreography by Balanchine"; click the title search improvement link there for more details.
OR, specifically search for:
"Great Performances: Dance in America: Choreography by Balanchine: Part 1 (#3.1)" (1977)
"Great Performances: Dance in America: Choreography by Balanchine: Part 2 (#3.2)" (1977)
"Great Performances: Dance in America: Choreography by George Balanchine: Part 3" (????)
"Great Performances: Dance in America: Choreography by Balanchine: Part IV" (1979)
This title represents both episodes of the TV series and films sold in VHS and DVD formats (NONESUCH).
