How to replace black borders with picture

[Alrod360]

I've seen lots of YouTube videos that have, instead of black borders, a picture on the sides. The game I am trying to record on has a portrait dimension to where when I render the finished product, it has black borders on the sides. Does anybody know how to change the black borders into something else?

 

[KdawgCreations]

you'll need a multi track software top layer video bottom a picture or something that's at
least 720 X 1280 to do that

 

[Alrod360]

you'll need a multi track software top layer video bottom a picture or something that's at
least 720 X 1280 to do that

Ok, now I know what to do, thanks

 

[SwingPoynt]

You can always stretch the footage too. It doesn't look bad majority of the time.

What's your software?