How Mirror Display Driver works for DirectX Video?


I have a mirror display driver for remote access application. When I play
video in Media Player it is vidible to client even if it is running in Full
Screen mode. When it is in Full Screen mode and I pause the video, nothing is
changing on Screen but Mirror Driver is still getting DrvCopyBits
contineously. What is this?

According to my knowlege when DirectX is running in Full Screen mode no
calls are given to Mirror Driver.

can anyone please explain what and how DirectX applications are affecting
Mirror driver’s working?