Apple Final Cut Pro X (10.1.2) - Manual (Page 370)

Chapter 11 Keying and compositing 370
6 Adjust the four corners of the mask to crop out the objects you want to remove, in this case, the
light stands.
When adjusting the mask, be sure to leave shadows and other details that can help make the key
more realistic later.
7 Apply the appropriate keyer effect to the foreground clip.
The foreground is composited over the background.
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