Check out this tutorial...
http://www.creativecow.net/show.php?page=/articles/brimelow_lee/video_basic...
If you want to preload a certain amount then you could use the ns.setBufferTime() method. How ever many seconds you specify, it will wait until then to play. So if you wanted 20 seconds to load first then you would say...
ns.setBufferTime(20);
Lee
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