I was playing around with my video camera and some scale models tonight. I wanted to try showing a plane flying over a model railroad scene. I used my WWI layout and a model WWI biplane. Since I don't have real chroma key green screen material on hand, I used green construction paper.
It took a few tries, but I ended up with this clip. It was a fun experiment. I suggest you put sound on and watch in HD.
The plane movement is choppier on this version. The choppiness could be due to the import from Adobe Premeire Elements 12 to iMovie. The green screen effect in APE12 Mac OS versions are very poor. iMovie does a better job with the green screen, but iMovie doesn't allow simple resizing of green screen elements. No good answer without upgrading to serious programs.