Hi
If you have applied a Zoom effect and the result is stretched it is probably because you did not check the Restraint: option in the Zoom parameters. This allows you to select a specific AR and will keep the zoom rectangle at the selected ratio when you make any adjustments to the outline. If you didn't make a selection then the sides of the rectangle are independant and the image is then stretched to fit whatever shape you create. If you don't want this to happen then set the Restraint to the AR of your video clip. e.g. 1920 x 1080 =16:9 1280 x 720 = 16:9 etc.
Nat