Apple Final Cut Express HD - Manual (Page 696)

696 Part IX Effects
For example, suppose the center point of the clip on track V2 is –218, –119. This puts the
clip 218 pixels to the left and 119 pixels up from the Canvas center point.
When you copy and paste these attributes to the clip on track V3, the clip appears in
exactly the same place. However, when you change its x coordinate from negative 218
to positive 218 (in step 12), you put that clip’s center point 218 pixels to the right of the
Canvas center point, which moves it to the other side.
Y offset
(-119)
X offset
(-218)
Clip center point
(-218, -119)
Canvas center point
(0, 0)
X offset
(+218)
Y offset
(-119)
Clip center point
(+218, -119)
Canvas center point
(0, 0)