I looked over the footage and did exactly what I described above and it seemed to work quite well. You will probably have to mask out the girl when you do the background track to keep the track stable, but filling the edges worked very well.
Keep in mind however that if you don't have any footage to cover all areas, you are still going to get black edges where there is nothing to replace (in your example clip the left side of the footage would remain black in a HD dimension for a few frames until the camera pans across).
Here's how I did it:
- Take your SD footage and comp it into a HD frame in your compositing package so you end up with black edges to the left and right
- Render this sequence out and create a project inside mokey
- In one layer create two closed rectangular splines that cover the exact height and width of the black edges. You may need to overlap the edges a tiny amount into the moving footage
- Create a background layer behind the first layer that covers the whole frame and uncheck the "Link spline to track" button
- You may want to create a third layer in between the background layer and the foreground edge layer to mask out any moving objects you don't want to effect your background track
- Track the background layer (selected only)
- Select the foreground and do a removal
You'll notice a fill starting automatically on the right hand side if there is a left to right pan.
Quality and amount of change in the background will obviously affect how well this works, but it seemed to do a reasonable job with the footage you supplied. If you would like the example I created, I will email it back to you.