L_DOWNLOAD_NOTICE is a notice which is to replace attachment if a user doesn't have permissions to view attachment files: <p><code>'DOWNLOAD_NOTICE'		=> 'You do not have the required permissions to view the files attached to this post.',</code></p>
Thus I decided to put _before event after this notice (as it rather looks as a part of post itself) because couldn't think of use case for such a notice.