Could Someone Explain This?

I know this must seem like a stupid question, but remember I'm new here and I still have a lot of things to learn. I was wondering if someone could explain the welding technique this guy is using in this video:
http://www.voodoo-people.com/~daz/mull/wmv/[email protected]
It looks like a spot welder, but in my limited knowledge I thought spot welding was for joining two pieces of overlapping metal.... not filling a gap between two pieces.

Anytime you are doing those short beads it can be called spot welding. Its a good technique for pretty welds that don't need to be strong or filling holes. Trying to patch a hole with a continuous bead is impossible. The heat just blows out the edge, so you do quick spots like that to prevent heat buildup.

spot welds can be used in body assembly to attach overlapping parts like doorjambs and rocker panels, or on external sheet metal in a flush, butt-joint. Again, it keeps the heat from warping or blowing out the sheet metal so it is easier to make it look pretty.

You're right anytime you do a short weld it can be called a spot weld. But in the movie that was using what they call a MIG welder. It is a continious wire welder. Spot welders (the real mechine) has to arms that pinch the metal between them and applies heat to fuse the 2 pecies of metal togeather mostly used in sheet metal fabrication like pots and pans and used originally used to weld cars doors in the factory.