I attached an example here:  Resized Image Example

I attached an example here: 

I found that resizing the DAR allowed me to convert the file, but no longer has the appropriate aspect ratio. I was hoping to basically have "black" on the sides with my resize without cropping the video.

I found that resizing the DAR allowed me to concat the two videos, but the resized portion of the completed video now has the wrong aspect ratio. I was hoping to basically have "black" on the sides with my resize without cropping the video.