Perhaps it is lost in translation, but video isn't film. So video surveillance probably means they placed a video camera (probably based on a video tube) and ran cables.
Lol. Kids. Video is certainly not film, but once upon a time was regularly recorded onto magnetic tape running over reels (google "VCR" or "VHS"). Still photography also used moving parts. Things like shutters would make audible clicks when exposing the photographic film, which then had to be moved out of position mechanically. That "click" noise on your iPhone camera is actually designed to mimic this ancient camera technology.
In an ideal situation. In a realworld situation that means running wires through walls, not something done easily in this situation. Hiding a camera in a bookcase is easy. Secretly running wires from that bookcase to a recorder in the next room is not.
They literally kicked his upstairs neighbours out and moved in there themselves. Once you’ve done that, dropping wiring down from your floor to his ceiling become trivial (at least for certain types of building construction).