Here's some pics so others will know what you're talking about and hopefully be able to help:
Original Video:
What
bullitt would like it to look like:
The reason YouTube does this is to maintain the aspect ratio of the original video so that objects in the video are proportioned correctly and not stretched. Basically so a circle looks like a circle and not an oval.
The only way I know how to do this would be importing the video into a video editing program such as Sony Vegas and stretching the video yourself...but I'm sure there is a much easier and cheaper way. :o