Hi,

I'm afraid, this isn't really feasible in Movie Edit Pro, at least not in any satisfying manner, both regarding to outcome and the way to get there. If you want a person or object in a motion video with basically no background and then possibly superimpose it over another background, you won't get around shooting that person in front of suitable single-colored background in the first place (especially "blue screen" or "green screen") and then making the background color transparent via chroma-keying. For a motion video clip, you can't just sit down and crop out a single object manually. That technique would be pretty much limited to the world of still photos.