When you use the Insert > Video/Media tool in the WYSIWYG editor, you can paste a YouTube or Vimeo link and LiveWhale will automatically recognize those URLs and supply the matching embed HTML.

You can extend this behavior to other types of pasted data:

$_LW->CONFIG['CUSTOM_EMBED_SERVICES']=array(array('find'=>'.*vimeo.com\/.*?((?:[0-9]+)(?:\?h=[\w]+)?)', 'embed'=>'<iframe width="{width}" height="{height}" src="//player.vimeo.com/video/{id}" webkitallowfullscreen="true" mozallowfullscreen="true" allowfullscreen="true" frameborder="0"></iframe>'));