For a non-technical end user, I find your instructions very easy to follow. I've run the script against a file I downloaded from You Tube rather than ripping from a CD. It shows that the file is save on a .mp4 file, which to my limited understanding, is a compressed version of a .wave file.
I am using Chrome and not Windows Explorer. But I turned on the View File Kind column in iTunes. I see a lot of MPEG Audio, AAC Audio, some PURCHASED files. That seems to be the majority.
So the original question remains: Is it safe to erase the Internet files I downloaded to a temp folder to add into the Song Info tab in iTunes without loosing those album cover illustrations?
Thanks.