One other possiblilty is the camera may have the audio bits setting wrong. Digital cameras can often record in 12 or 16 bit audio formats, so if yours has a selection option for this, try setting to the opposite and then download the movie again.

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Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."

System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70