welding 101

I just watched the video and some of the information needs adjusted.
It depends on what wire you use on whether or not to weave or oscillate the weld puddle. It also depends on the joint configuration.

Weaving or oscillating with a flux cored or shielded wire tends to trap slag in the joint which may weaken it.
Also with many wires its best not to push the puddle but to either go straight in or drag it with no more than 10* layback. Dragging has the same effect as weaving as it allows for the puddle to fill without undercutting or under filling the base material. Also, weaving will put more heat into the joint causing more warpage, or misconfiguration of the material due to a slower travel speed.

But, I guess the video is made for beginners, lol :)