There were a number of threads in the past couple of years, but they were mostly discussing the use of weights to counter balance the camera when using a filter that weighed too much. The heavier filters were causing the pitch motor to overload, and cut out. The result of that was a camera that would hold level, then drop straight down. It seems like the pitch motor would kick back in, then the process would repeat.
AFAIK, the only effect of the added weight is on the drone itself.