Disclaimer, I know nothing of the internals of Microsoft RDP, but it does not appear to use an image representation like VLC, etc. do. My suspicion is that Windows APIs are intercepted and used to build the desktop experience. Don't get me wrong, I know A LOT about Windows internals, but I never looked into that part, sadly. What I do know is based upon what I see, and what I see leads me to the comment above.