I had this same question. The confusing part is what Scott says in the second video of Module 4 Unit 5 where he is talking about shorts and shunts about a 1:30 in. He says that in the case of a short, current will still flow both paths since voltage is present, but that it would only happen for a fraction of a second because the breaker would trip. If it were the case that current flowed both paths, I did not understand how a shunt would work at all. The fact that a branch with zero resistance breaks the laws of parallel circuits and it takes all the current down that path cleared up the confusion I had from the earlier video.
