Streaming Video In MX Question

I have a set of video files created in Flash, created from importing decent size MPEG files.

You can see the actual results here. http://www.wecommit.com/media_library.php

As you may have noticed, they wont play until the entire file is downloaded to the user. I was under the impression that they would start playing as the data was received but I am probably mistaken.

What is the best way for me to tell FLA to load about 500 or so K to the user and then playing, while the rest downloads as they go?

Thanks much for any help you can give.