Step 1: The greenscreen

Step 2: The original video
Step 3: First overlay attempt
Step 4: Greenscreen artifiacts are removed by changing the white balance of the overlay
Step 5: Change lighting to match greenscreened image, add Depth of Field effect, render video.
Step 6: Restore rendered result to original lighting
So there you go, that's your update for April 1st. And it's no April fool's joke (or is it?).