understanding rtmp buffer size

When streaming an flv to flash, I am not sure I understand the feedback from the NetStream buffer events listed here.

This article from Adobe suggests tha开发者_如何学JAVAt the files are never cached to disk:

"When RTMP-based video streams into the Flash Player, the audio and video data is only stored in the Flash Player's memory buffer"

Specifically, what does setting a buffer size of 3 seconds mean when a video is playing? Does flash always try to have 3 seconds of pre-roll?

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That is it really:

1. Does not get stored to disk
2. The buffer size controls when the buffer full event will be fired, so that the interface can stop the video and show the loading component.
3. The stream will be paused when the buffer size is smaller than then specified buffer, and played back when it's larger.