I've created a presentation using Keynote '08 from Apple's iWork. I recorded an audio voiceover and exported a .mov file. However, since I recorded the audio in multiple takes, Keynote exports the file with multiple (AAC) audio streams. YouTube doesn't accept videos with multiple audio streams. It simply uses the first audio stream so that after a few minutes, the audio drops out.
How do I convert this video into a format that can be uploaded to YouTube?