Apple Final Cut Pro 7 - Manual (Page 76)

76 Chapter 3 Preparing Clips in the Viewer
Click the Motion tab and click in the keyframe graph area to position the playhead near 7
the end of the clip, then click the keyframe button to set another keyframe.
Add a keyframe here.
Press the Down Arrow key to move the playhead to the end of the clip, and set another 8
keyframe. Set the opacity to 0 (zero). The keyframe graph area should now look similar
to this:
Add a last keyframe here.
Choose Window > Arrange > Standard to resize the Viewer. 9
Press Option-R to render the clips, and then play the sequence in the Timeline to see 10
how the text appears and then disappears based on the keyframes you set. Experiment
with making changes to the keyframes and Opacity parameter settings.