Oh to return to the times when Disney actually had ambition.
This is actually an edited and spliced version of two separate videos. One is 1978, but the other is much later - you can see the transition around 2:30 when the new narrator kicks in. That version of Epcot was much more similar to the opening-day shows.
@Bob_Shaw Yes, some of the artwork was by McCall! He worked on the Horizons pavilion, which you see toward the end of the video.
God I loved Epcot...