Down and Out of District in Beverly Hills - S2-E12
Visible crew/equipment: Kelly, Steve, Andrea, Brandon, and Dylan are all gathered near the lockers when Kelly begins to discuss her opinion of Steve's new girlfriend Christine. Just after Steve says "Tell me everything that's wrong with Christine", the camera pans to Kelly where a microphone becomes visible at the top of the screen. (00:15:15)
Answer: There was no explanation. Usually, when a show doesn't know if it's going to be picked up or not, they will use stock footage until they can spend the money on a real location.
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