Linux + phonon + phonon backend (GStreamer) QtWebkit if video stream was reached end of stream, play control is not work anymore. On the contrary, play control could be repeatable, when video stream is on the middle of stream.
Please follow http://trac.webkit.org/wiki/QtWebKitBugs when reporing bugs here (missing Qt keyword).
We don't fix Phonon anymore, QtMultimedia being the default. If you want you can make a patch for it and re-open the bug.