Making changes in the Simulation Videos

I completed a step-by-step simulation only to be then told by my manager that one of the staff photos in the simulation video needs to be removed.
I have watched some videos explaining how to make edits to simulations to remove sensitive information, however, this only works on text and still images.

I went to the media library and found a series of png images, which I hoped were the entire video, however, after editing these (replacing the photo) I found that the old photo still appeared in frames during the simulation.
If I could access the original video, I could edit it, however, there doesn't seem to be a video anywhere (unless I export it), which doesn't solve my problem, because I need to edit the simulation video itself.

Any suggestions?