This is very useful and can be used to achieve more than one type of effect. Track Motion is used to change the position that videos of a track will take on the video window. To show you how this is done let’s play around with a random clip:
As you can see on this clip Sara is on the left side of the screen but for whatever reason let’s say I want her on the right. This is where the Track Motion would be of help. Click anywhere on the track and on the main menu go to Tools >> Video >> Track Motion
After clicking on it you will see this window:
That box in the middle is telling me what position the videos on this track have. I want Sara on the right so I don’t want it centered like it is, so what I’m going to do is drag that box to the position that I want, like so:
After that just close that window and we should have Sara on the right of the screen! Now take a look at the clip we just made:
Note: Keep in mind that whatever changes you make with this will be made to track and therefore all video clips that you place on that track will behave in the same way.