I'm using a custom getter in Page.php like:
public function getContent(){
$ret = $this->getField('Content');
$ret = str_replace('<p><iframe','<iframe', $ret);
$ret = str_replace('</iframe></p>','</iframe>', $ret);
return $ret;
}
But I guess the cleaner solution would be editing the 'valid_elemnts' of TinyMCE in _config.php like:
HtmlEditorConfig::get('cms')->setOption('extended_valid_elements' , '*iframe[ * ]'); //Don't know if it's really *iframe[ * ]