sometimes, the scale, postion keyframes that were tracked can be jittery because of the quality of footage. In that case. And there's an expession you could apply on that propery to smooth out those jittery motion keyframes. alt click postion/scale stopwatch, type in 'smooth()'. This will smooth out the keyframes and you can see the change when you look at the curves in graph editor!
This is great video. It explains it very, very, very clear. But, somehow it did not work for me. I wanted to match a movement of a graphic and it did not work. It just went far away from the subject. I changed the position to the right, just like you and it just went some place else. I closed everything and started all over again. It gave errors this time. It could not process. Then, closed it everything to start again and nothing. It would process this time with all the key frames and connecting the graphic to the null and nothing. So, I had to do it manually, frame by frame. I am using the lastest version of AE. Thanks for all these videos.
