Hi,
I tried to play a vedeo Avi in Windows XP using QT4.

My code is very simple:

QString fileName = QFileDialog::getOpenFileName(this, tr("Open Movie"), QDir::homePath(), NULL);
Phonon::VideoPlayer *player = new Phonon::VideoPlayer(Phonon::VideoCategory, ui->graphicsView);
player->play(fileName);

I have no errors, but starting the program nothing happens, the graphicsView remains empty and the video does not start.

On Windows XP I loaded the video codec, in fact the video start normally using any video player.