I recently built my first Flash Player and so far it works great. When I switched from playing a locally stored video to a video stored on Amazon S3 it stopped working correctly.
Before it would start playing as soon as enough of the video was downloaded. ie. playWhenEnoughDownloaded()
For some reason when attempting to play a video stored on Amazon S3 it will download the entire thing before starting. I do see the progress of the download so it seems it can figure out how much is loaded.