Does anyone knows the Wordpress hook used to modify the HTML code generated by WP's Add Media -> Insert from URL -> Insert Into Post function.
To clarify myself, let's say I want to add a media into WP's editor via a URL. So I click on Add Media then pick Insert from URL, enter my URL, Link the image and Insert into post. This generates an HTML code in the editor. Now, what I wanted to do is add rel="lightbox" in this HTML code.
I'm able to do this for the Add Media from library action using the hook "image_send_to_editor", but this only seem to work as long as the Media is in the Media Library. The Insert from URL function seems to be using a different hook.