Originally Posted by
QuarterInchSocket
It is possible that the cab diff press sensor can sense the subtle cabin pressure change due to toilet flush (an induced pressure leak). I would have thought, that the flush would cause the needle to dip to a lower pressure momentarily, however, there might be a phenomena/characteristic that im forgetting that causes a sudden rise in pressure when the flush valve changes state from closed to open.
Perhaps when the pilot on the video said the gage briefly rises with a flush they were talking about the cabin altitude change rate or cabin pressure altitude needle rather than the differential pressure needle?