You cannot physically 'move' the first
video clip and leave a blank space
on the timeline.
Add a black photo to the timeline
and adjust the duration as required.
Just use an image editor to fill any
photo with black and save it under a
new name...'background' might be a
good choice. Then import it into
J. Inzer MS-MVP
Digital Media Experience
This is not tech support
I am a volunteer
Solutions that work for
me may not work for you
Proceed at your own risk