I wanted to add an id to the swfobject wrapper so I used:

$args = array(
...
  'othervars' => array(
    'id'=>'home-flash',
    ...
  )
...
);

It "worked" by making 'swf-home-flash' the id of the swftools-wrapper div but it also added the plain text id="home-flash" in the params area. This made the text appear above the flash object when it was rendered.