The VideoLAN Forums

Had a problem with YouTube.com videos - no sound. After searching around the Net turns out others had this problem, and it told me that VLC sets the audio output frequency to 96K. Even a restart doesn't reset this. Using the Audio MIDI app in the Utilities folder to reset the freq to 48K will fix things.

This could easily be called a YouTube bug, but perhaps you can modify VLC to not do this, or add a setting to not do this, or reset the settings back on Quit.

You must have been using an old version of VLC. This behaviour should no longer be a problem.

This wasn't limited to just VLC either. I saw this same behaviour with a Flash upgrade as well (turning the sampling rate to 96k), so I suspect they might have had something in common (a legacy call perhaps?)