Hi! Great plugin but I noticed strange behaviour when calling a list of excerpts. The excerpt will show the style-code coming from mime-type, even if there is no attachment to the post.
The problem is that you use a global variable
$add_attachment_style that is not reset between calls. So it stays true, adding style code to all calls to the_content() thereafter on the same page. The fix seem to be to simply reset
$add_attachment_style in beginning of