This is a PBS special from 1986. Though dated in some ways, it still holds up as a great explanation of the gothic style and the basic concepts of cathedral construction of the medieval period. It also gives some idea of life in a medieval town.
From the DVD jacket:
Author David Macaulay hosts CATHEDRAL, based on his award-winning book. Using a combination of spectacular location sequences and cinema-quality animation, the program surveys France’s most famous churches. Travel back to 1214 to explore the design of Notre Dame de Beaulieu, a representative Gothic cathedral. The program tells period tales revealing fascinating stories of life and death, faith and despair, prosperity, and intrigue.
The book from which it is based was first published in 1973.
Naturally one would expect a program like this to focus more on the construction and unique stylistics characteristics of gothic cathedrals (suited more for the tourist than the worshiper). And is does do that. But one also gets a sense of the purpose of cathedrals and how they expressed the Christian faith and beliefs of the people.
I found this video because I am trying to educate myself on the meaning and purpose of Christian architecture.