Im not exactly sure what your trying to do, but it sounds like you are trying to take a show that was broadcast in 4:3 and convert it to 16:9, only way to do this is to squish the image (not good) or crop the top and bottom (also not good)

its not about having something in widescreen, its about having it in its OAR (original aspect ratio). when you see shows (like tv shows) on cable that are shown on an HD channel in widescreen (16:9) and on a regular channel in 4:3 these are filmed in 16:9 (or for 16:9 in case of open matte, not sure if they use open matte for tv shows) and then cropped, pan & scanned, or such to show the 4:3 version.

in short, if you captured it as a 4:3 you should leave it as a 4:3 because its either already been cut up so cropping it more would loose even more picture or 4:3 is its OAR

-Darth Simon