Couple of things.........
First, it's not a "copper guard", it's a nozzle.
Second, like BB88 said, many welds are done one handed. The position of the weld usually dictates what you do with your free hand.
Third, type of weld and material thickness will dictate how much you need to work the puddle by "stitching".
If anybody was gonna rip on this guy, I thought these things were ripe for target practice:
1) No mention of cleaning off the parent material.
2) Water quenching. Usually a no-no.
3) What's with the "grind it off" statement at the end?
Obviously not meant to be an all encompassing tutorial.