It seems to me that there is a bug: everything works perfect but only with Linux. SWFText crashes while working on Windows. So I do it that way:
<?php
$f = new SWFFont('Arial');
$t = new SWFTextField();
$t -> setFont($f);
$t -> addString('Hello world!!!');
$p = new SWFSprite();
$i = $p -> add($t);
$i -> moveto(100, 100); $m = new SWFMovie();
$m -> add($p);
?>
Of course it writes text where I want, but I still can't get other methods of SWFText class. For example: I can't get text width (swftext->getwidth).