If you like to add a icon to editor tooldar then do this:
Find on editor_toolbar_on template this:
Code:
<td><div class="imagebutton" id="{$editorid}_cmd_wrap0_html"><img src="$stylevar[imgdir_editor]/html.png" width="16" height="16" alt="$vbphrase[wrap_html_tags]" /></div></td>
Add bellow this:
Code:
<!--custom bbcode youtube start -->
<td><div class="imagebutton" id="{$editorid}_cmd_wrap0_yt"><img src="$stylevar[imgdir_editor]/youtube.gif" width="21" height="20" alt="Wrap [yt] tags around selected text" /></div></td>
<!--custom bbcode youtube end -->
Upload the image in to your style editor folder:
Thanks a lot!!