Have you applied a great effect only to have it chopped off at the edge? Certain effects cannot extend beyond the borders of an image, one workaround is to import the files as a Composition and choose to NOT crop the layers . But chances are you've already imported and animated, so here's another way:
Select the footage item.
Choose Layer>Pre-Compose or press Shift+Cmd+C (Shift+Ctrl+C).
Choose to Leave All Attributes behind.
Click the Collapse Transformations switch to extend allow the effect past the edge of the border.