Apple Final Cut Pro X (10.1.2) - Manual (Page 369)

Chapter 11 Keying and compositing 369
3 Select the foreground clip.
In the above example, the light stands need to be removed.
4 Click the Effects button in the toolbar.
5 In the Effects Browser, double-click the Mask effect to apply it to the selected foreground clip.
Tip: Type “mask” in the Effects Browser’s search field to quickly find the mask effect.
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