How do i take out just the voice of the video?
I would want to take out his voice from the video so i can put a picture while he is talking. For Imovie
So you want his voice to continue while you superimpose a picture? This is called the Cutaway feature.
Here is a good Tutorial.
http://www.kenstone.net/fcp_homepage/imovie_09_stone.html#cutaway%20pip