In Motion Tracking, you can attach an effect to an object, such as attaching the "Mosaic" effect to an object surrounding a persons face in order to hide their identity. When I tried this feature, I didn't get the results I expected even though I followed the instructions of dragging the effect to the object in the preview monitor. The Mosaic effect was stationary and did not follow the person's movements.
What I found out is the Mosaic effect was placed after the "Mask" effect in the properties panel. Adobe should have placed the Mosaic effect before the Mask effect. After making the correction by dragging the Mosaic before the Mask effect, the effect worked as expected.