[wp-hackers] Problem with custom TinyMCE button

[Andrew Ozz]

Did you add 'video' to the extended valid elements in TinyMCE? If no, 
something like this should work:

function my_extend_mce_settings($a) {
   if ( isset($a['extended_valid_elements']) )
     $a['extended_valid_elements'] .= ',video[*]';
   else
     $a['extended_valid_elements'] = 'video[*]';

   return $a;
}
add_filter('tiny_mce_before_init', 'my_extend_mce_settings');