Totem losing sound after a few seconds of playing

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http://askubuntu.com – After starting Totem in Ubuntu 12.10 (playing an .MTS file), it starts out playing just fine, but after about 3 seconds the sound goes away. No clue at all what is happening. .MPG files play just fine. The videos play just fine, with sound, in VLC. EDIT: Pausing the video and then starting again brings sound back for about one second, and then the sound fades again. (HowTos)