str_replace for the_content()

Hi I would like to do a replace on the_content to add a parameter to youtube posts of wmode = transparent so it doesn’t confict with some drop down menus.

Obviously this doesn’t work because the_content echos the value, but this is what I would like to accomplish.

$content = the_content('Continue Reading »');
$embedText = '<param name="wmode" value="transparent" /><embed wmode="transparent"';
$content = str_replace('<embed ', $embedText, $content);
echo $content;

Thanks for any help
j