I had a hard time finding a way to stop a sprite, so I figured I would post it.
$button = new SWFButton();
$button->addShape($box, SWFBUTTON_UP | SWFBUTTON_HIT | SWFBUTTON_OVER | SWFBUTTON_DOWN);
$button->addAction(new SWFAction("
setTarget('box');
stop();
"), SWFBUTTON_MOUSEUP);
$item = $movie->add($button);
This works the same way with play();