Hi Glen
Your film downloaded (but didn't show the image I posted above,,,,,which I find a bit weird. What I did get when it had downloaded was a small picture of Dorothy overlaid by truncated text.......The sound track was Prose....

Is this your project or a download/upload cockup by Google??
Whatever......
If you research Google images you can get the original and load it to VP. The one shown above is cropped. The original is 16:9 (298 x 169 which may be a bit small for full screen)
VP loads this full frame.......

You can now add your text........

You can monitor this in the Sequence Preview window.
Export as mp4 Custom Wide screen TV..........(or select one of the 16:9 formats)

As seen in VLC
Is this the sort of thing you are aiming at?
For full screen images try to get a 16:9 format. If you can't then you can use the Zoom effect on the clip restrained to 16:9 to get rid of any black borders. You can move the zoom area to outline the required bit.
If it is the text you are not getting correctly then let us know..
Nat