I found a bug in Qt Phonon library. I have made a remote videos player based in Phonon that it stopped working after a several executions. It is necessary to make a hard reset to the remote videos player works again.

The code:

Phonon::MediaObject* media = new Phonon::MediaObject(this);
Phonon::VideoWidget* video = new Phonon::VideoWidget(this);
QVBoxLayout* layout = new QVBoxLayout(this);
layout->addWidget(video);
Phonon::createPath(media, video);
media->setCurrentSource(kMyUrl);
media->play();