And I thought my school's 1980-something Jands lighting system was ancient...

What kind of equipment? I'm a theater tech and find your theater shots fascinating (especially considering that most of the gear I work with is almost as old as the gear in your photos :p)

rich_edwards, Laserdiscs were one of the various video formats available in the '80s - they actually predate CDs by a few years. They are the size of an LP, and are recorded on both sides.

My understanding would be that the switches would be left in the 'on' position, and in event of a power failure, the battery would automatically cut in. The switches were probably to cut off power to lights if they were being worked on.