I've seen those codecs, but i didn't know that this is the w32codecs.
No, i'm not a Kubuntu user. But plan to try KDE in the future.
Here's a 2-step solution for the language problem if you still have the 64 bit Firefox installed beside the 32 bit Firefox.
Copy the language pack(s) from
(Editing the appropriate line in about:config does not work.)
// Use LANG environment variable to choose locale