Size of video file display

I initially had problems getting DirectRT to display video (.wmv) files in the correct size. I had adjusted size parameters in DirectRT, the style file, my video program and even the bitmaps from which the videos were constructed, none of which solved the issue.
The problem turned out to be a default setting in my video editing software (Sony Vegas 6.0). The video software maintains an aspect ratio appropriate for TV screens, unless you specifically un-select this option. This aspect ratio means that the video stretches to the sides of the specified DirectRT display area, but does not fill it at the bottom and top. This is true even if the pixel size parameters I specify for the video indicate a different aspect ratio.
(In Vegas, the way to disable the default is to right-click on each particular component frame, go to Properties, and under the header Switches unclick the item Maintain Aspect Ratio).

Thanks for the tip!