If it doesn't distort the video or create undesired black borders, export at a different resolution/format. 640 X 480, for example, results in the old TV 4:3 presentation.
To crop instead, you might import a video to VP, drop it onto the timeline as a single clip, then click the FX button at the bottom-left of the clip.
The effect box opens. Click the far upper-left green + sign and choose CROP. In the preview window, drag the handles (dots) to the size desired.
