A couple of ways:
A. Import your rendered frame sequence and save it out as a swf file. Then in your main movie, you create a blank movie clip and dynamically import the swf as streamingwhen needed. This keeps the main movie light. You'll still need a preloader for the imported file if it's large.
B. Render your frame sequence and save it as a video in a video editing app. Convert to FLV using Flash utilities and use the video component. This is only if you just want to show the animation...if you need to interact, use the first method.
Some folks use hosting with Flash communication server to hold the heavy files and heavy actionscript to stream.
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