Yes I have exiftool installed.
The edited lines are:
+"_____\n->Location of exiftool:", r"/usr/bin/exiftool"),
(PF_FILE, "text_editor", "->Text editor to use for '__ OTHER OPTION __':",\
As you can see is gedit in the same directory and it shows up in the plugin dialog but exiftool not. If I choose the path manually its accepted.