Not to be snarky, but it is "Album Art", not "Artist Art".

I, personally, don't understand why you would not have your music tagged, but I am confused on what exactly you have on this point:
In the first post you state "if i have 30 albums from one artist i have thirty pictures in this plugin - one for each artist is more practical" - implying to me that you
do have album tags written, then you say "i meant that pictureflow cant display folder.jpg if there is no album mentioned in the mp3-tag", implying you don't.
Are you saying, though, that if you have a folder.jpg file in the same folder as a collection of mp3s w/o and album tag that pictureflow
won't use the folder.jpg? I haven't tried it, but as I understand the situation
it should.