I didn’t watch Big Love - and so I am not certain which ceremony was depicted. There are different ordinances that take place in a Mormon Temple.
There are eternal marriage ceremonies,
Endowment ordinances,
Saving ordinances of the dead that includes baptism, endowment and marriage etc.
There are special words, new names and handshakes that one learns. Each is representative of what Mormons consider part of eternity. There is a movie that plays that depicts the creation (according to Mormonism) and describes the “counsel of the gods” in heaven - how the earth was organized (as opposed to created) - how satan was part of god’s plan to tempt you so you could show how worthy you of of god’s promises etc. When I attended the LDS Temple this movie was actually a play where temple workers depicted the parts of Satan, Adam and Eve and Michael.
As I said, I’m not sure which of the ceremonies was being depicted, but you can find your answers on the internet via many sources. here is one http://frombehindthezioncurtain.blogspot.com/2008/08/mormon-temple-ceremony-observations.html
It was the circle at the altar (the old “pay lay ale” part) and then the giving of the signs and going thru the veil in to the Celestial Room.