Problem media_send_to_editor

Hey guys !
I actually got a problem with one of my plugins in 3.5 RC3
This one use the following code, but it don t works anymore:
When i send it to editor, it dont change my class in “html mod” in post page.

function highslide_integration_send_to_editor( $html, $send_id, $attachment ) {

   if( isset($_POST["highslide-$send_id"]) )

      return str_replace('<a', '<a class="highslide"', $html);

   else

      return $html;
}
add_filter( 'media_send_to_editor', 'highslide_integration_send_to_editor', 66, 3 );

Someone got an idea ?