Comment 5 for bug 594966

When trying to produce the small attachment I actually learned a work-around for the problem.

I a file has the noisy sound, you can try

ffmpeg -i file.flv -vcodec copy -acodec copy copy.flv

The copy plays nicely. (ffmpeg needs to be installed separately. I have the medibuntu version, but I'd assume for just copying the streams the Ubuntu version should be enough.)