Disclaimer: I didn't watch the video so this response has nothing to do with it's content, just my reaction to the question in the title.
If we did (and that's a big if) come from outside our planet, then I think it would have been more like the movie Evolution. In that alien life lands on earth in the form of single celled organisms on a meteor and evolve into a full eco-system from there. Of course in the movie their evolution was accelerated, but that's beside the point.
