[aibon]

to disable custom bbcodes in the signature add this hook:

Hook bbcode_parse_start

PHP Code:

if ($forumid==='signature')
{
    unset($this->tag_list['no_option']['youtube']);
} 


that's a example for a custom bbcode tagged youtube with no option. if you have a tag with options use option instead if no_option. to disable more just add more lines with the tags.

Important
because signatures are precached, you have to do the following:
disable and then enable bbcodes in the usergruppermissions after adding the plugin to clear the cache!