On the upgrade site they include a brief video showing a Portrait image with what they call Border Effects to kind of embedded the narrow portrait image into a wider-screen shot. In a way, they show the border(s) echoing aspects of the narrow image in order to fill out the width of the frame.
"Attractive video border effects From now on you can use the portrait format recordings from your smartphone without compromising your video's look. The new image border effects ensure perfect integration."
(ignore the play-arrow overlaying the still image - a screen capture.)
I am not sure how to accomplish this. Any info would be appreciated.