I've got a 7 minute flash animation, and the audio (a single WAV file, set to stream) plays out of sync with the video once it's exported to SWF.
It starts in sync, but by around the 2-minute mark it's noticeably out, and by the end it's ridiculous.
I read some suggestions that if I upped the bit rate of the exported audio, the sync would improve, but this doesn't really seem to have worked.
If I export the SWF with uncompressed audio, then it plays fine, but the file is way too huge to put on the internet.
Use shorter audio files. Break up the audio into shorter, more manageable chunks, and then place those shorter audio files in your movie.