Well, folks, here's something that really works and is really easy.

1. Render your video at 640x480. This is a common size, but actually you only need 480x360, but any resolution higher will work and since 640x480 is commonly used, use this for dimensions.

2. I've seen some how to vids about this that say you should render to DivX or H.264 for windows. I'm not sure that this is necessary, 'cause I rendered to WMV for my latest video and it worked fine.

3. After you've uploaded your video, PLEASE WAIT. In a hour or so after it becomes available, it will also be available at high quality. You will see a link at the bottom right hand corner of the vid that says Watch in High Quality. You can use it, but it doesn't quite cut it. Your video will look better, but it will not sound better.

Here's the kicker.
4. After the video shows the 'Watch in High Quality', you'll be able to do this and get superb results in both video and audio quality. Append &fmt=18 to the url shown in your browser's address bar. BINGO! You have excellent video and sound quality!

Try it! It works. It works on any video that shows the 'Watch in High Quality' link.

Here's my latest YouTube submission

YouTube - Glenn Miller's Chattanooga Choo Choo

Here it is with the appended code

YouTube - Glenn Miller's Chattanooga Choo Choo

Big difference eh? And the uploaded video was a WMV!