Flash files don't stream - they start playing only after download. The good news is - the movie doesn't have to wait until it's ENTIRE content gets downloaded, you can create it in such a way that it'll start playing as it comes. I think you'd need to break it up into separate smaller movie clips that get played as they are loaded... Look it up on Flash support sites.

In either case, Flash player will have to wait until the entire current movie clip is downloaded. When you see one of those countdowns, that's a different clip playing waiting for the main one (or next one) to download.