Im watching some youtube videos. mainly on automotive modeling which I would like to do, they use this technique to blend 2 surfaces together but I don't quite understand what going on, mainly cos language difference and is not moi 3d.
but maybe its possible to do something similar a different way.

I took some screenshots





firstly two surfaces not connected intersecting


at this point seems to lay plane over top


plane gives impression surface is blended, even tho geometry is still underneath


final frame is like this, this I see often sometimes on car models.



this is me trying to understand and duplicate what I see. I projected curves then sweep a curve to create blending effect.
does anyone understand what is being shown and can help me understand.

link to video if needed http://www.youtube.com/watch?v=WszmgbohMZs