The Media Block field gets presented when creating a new page-type campaign:
For existing page-type campaigns Media Block can be accessed when editing the campaign. The Media Block field can be found next to the ‘Media Block URL’ line item on the page-type campaign ‘Edit’ page.
To add a SlideShare presentation enter the SlideShare presentation URL into the Media Block field. Here is how to do this:
SlideShare is a service of SlideShare, LLC (slideshare.net).