Which one of the following statements most accurately characterizes a difference between the two passages?

I have a question about the second argument. Anyone named Sue is a girl. X is named Sue. X is a girl The question I have is you initially call it a valid argument, you assume the premises to be true however when you introduced the Johnny cash song (which no song will be occurring on the LSAT) you change it to a flawed argument. However you call it a flawed argument, I thought the purpose of this section was to determine if the arguments were valid (good) or invalid (bad). However you are introducing that the argument is flawed with a SONG - which is never going to occur on the LSAT. We assumed the premise to be true, and it was a valid argument before the johnny cash song, however there will not be a johnny cash song playing on the LSAT, what benefit does playing the Johnny Cash song have in determining whether or not it is valid or invalid? (NONE) I thought that was the purpose here, not to go off on some tangent about it being flawed or not with a song which will never occur on the LSAT. So is it a valid argument that is flawed? Or just a flawed argument that isn't valid anymore because it is flawed. Also the third example. (It is cold. It will snow) I understand that it is an invalid argument because the conclusion does not follow logically. But why is it flawed? And what is the purpose of talking about flaws this early it only has confused me.