Is there a way to take a full screen production and make it into a wide screen production? I wanted to do so, and then re-record in full screen so I can add effects in the black bars above and below my production.
If I interpreted what you want to do as take a 4:3 ratio video, letterbox it to 16:9 and then put this back into a 4:3 ratio so that you get a black border top and bottom but not left and right.
Is this correct then you do not need to go the long way round to get what you want - all you need to do is crop the video top and bottom.
Which ever way you do it you are going to lose some of the image.
If this is not what you are trying to do come back with more detail giving the video ratios rather then 'full screen' , 'widescreen' - these terms have different aspect ratios depending on the context they are used in.