Making a traveling matte

1. Open 16-5.prproj.
2. Drag the face matte to Video 3. Stretch the face matte clip to the same length as the other clip.
3. Select the face matte clip and then expand the Motion effect in the Effect Controls panel.
4. Set a Position keyframe at the beginning of the clip by clicking the Toggle Animation button to the left of Position. Position the white circle where the woman's face.
5. Scrub the Timeline to about the halfway point of the clip and adjust the matte to be over the woman's face. Move halfway across the remainder of the clip and do the same thing again. Continue setting keyframes until you can scrub the clip and have the matte over the face at all times. (figure)
6. Select the Video 2 clip, select Video Effects > Stylize, and apply the Mosaic effect to it. Set the horizontal and vertical blocks' values to 30. This makes the clip in Video 2 a mosaic.
7. Locate the Track Matte Key effect in Video Effects > Keying and apply it to the clip in Video 2. This is the same clip to which you applied the Mosaic effect.
8. Set Matte to Video 3 and Composite Using to Matte Alpha.
9. Play the sequence.