1) try to use brackets.
system.method.insert=movedir2,simple,"d.set_directory=$d.get_custom2=;execute={mv,-u,$d.base_path=,$d.get_custom2=};d.set_custom2=;d.stop=;d.start="
2) try to add spaces after semicolons.
3) try to use your own script instead 'mv' and check inside - is it called, what...