Starting a video visit with the Microsoft Surface Pro sometimes results in the camera showing what's behind the screen instead of what's in front of it (in this case, you). You end up seeing the doctor, but the doctor ends up seeing the other side of your device.
To remedy this, go to the lower left of your screen, and click where it says "Settings". There should be a choice for "Front" or "Back", which corresponds to your camera. Click on "Front" to activate the front camera, and this should remedy the problem.