Thanks again zoppo.
Tab names and threading preferences appear to be missing from your ts file. Running lupdate should fix these.
lupdate -noobsolete avidemux.pro
You\'ll need to translate some of Qt for the OK/Cancel buttons, etc. The translation file can be found in Qt\\4.3.2\\translations\\qt_untranslated.ts. Take a copy of it as qt_it.ts. QDialogButtonBox and QFileDialog are probably all that is required. To test, copy the compiled qm file to Avidemux\'s i18n folder.
Everything else should be fixed in r3642.