I've committed FFMpegCodec, WavCodec, Codec, AudioClip, AudioManager, RingBuffer, and an updated WGETest to svn.
It now requires boost::date_time and boost::thread in addition to boost::python. Also FFMpeg would be good too.

It needs a test file for FFMpegCodec (I didn't have anything that I could distribute) in wge/build/WGETest/Media/. The demo is set right now to use "test.mkv", but you can just set it to anything audio or video that has audio.
I never found the source of the stuttering, though I can rarely reproduce it. I'll give it a try on some other computers when I get a chance.
If you end up testing this, let me know how the threads behave as I'm on a quad core.