How to Motion Track Text in Adobe After Effects

1. Drag video clip into timeline.
2. Go to main menu and select Window > Tracker Controls.
3. Observe a Tracker Controls panel appearing.
4. Go to main menu and select  Layer > Null Object.
5. Select clip in timeline and click Track Motion button in Tracker Controls panel.
6. Observe a tracker box appearing in the preview window.
7. Position the Tracker box on an easily recognisable good-contrast object.
8. Click Edit Target button in the Tracker Controls panel.
9. Select the Null layer and press OK
10. Click the "play-like" button called Analyze Forward in the Tracker Controls panel.
11. Observe the preview monitor playing and analysing. It will take some time.
12. After analysing, click Apply in the Tracker Controls panel. 
13. Select X and Y and click OK.
14. Observe a lot of keyframes generated in the preview monitor.
15. In the timeline, expand the null layer and select all the keyframes.
16. Press keyboard F9 to turn the keyframes into easy ease keyframes.
17. Add a text layer, type in your text and modify text whatever way you want.
18. (optional step) In the timeline,  select text object and click T icon. Drop the opacity down to 50%.
19. (optional step) Position the text wherever you want.
20. In the timeline, select text object and connect the pick whip (spiral icon) to the Null object).
21. Play back to watch the the Motion Tracking in action.