In a project page as this:
http://translations.joomlapt.com/languagepacks/allvideos/pt-PT
the link "Help improve this language pack" goes to nowhere in the Transifex page as it points to
https://www.transifex.com/projects/p/allvideos/language/pt-PT/
but should point to
https://www.transifex.com/projects/p/allvideos/language/pt_PT/
(note the underscore in the language code)