Did either of you ever get a resolution? I have made some progress but am looking for more. There is a plugin called “Amazon S3 for WordPress”. This allows you to use S3 as your native wordpress media library so that it handles the authentication with S3. You can then use a FLV plugin for wordpress and use the URL for the video provided by the WordPress media library. I have tried it using a quick time .mov or .m4v file using embedded quick time player and a FLV with a FLV plugin. Please contact me if you would like to share more information.
To use Amazon S3 for wordpress you must first have a S3 account and set up at least one bucket. I used S3Fox for that.
