That does sound vaguely familiar. I guess all the editing was done in analogue for Ten's entire run, despite being broadcast on digital from the get-go.
I found
this article from 2007 (have a read, because I wonder how the staffing numbers at Seven compare):
More than 6000km of video tape is used in the production of Big Brother. Six video tape machines run simultaneously to record all of the action in the house.
At a guess I'd assume Nine switched to digital cameras and storage when they resurrected the show?