Modular Drupal content-type (variable sections)
You can do this with the Field Collection module.

Add a field collection to your Case node and then add then add fields of the types you require to the field collection restricted to the amount of images or videos you want to display. An with the correct image styles assigned.

You could use the Field Group module to collapse the fields to improve the admin interface.

Edit:

Another option would be use Conditional fields module and add image fields to the case content type set the the amount of images to be displayed in each and the image style required. Then add a list field to the case content type with option on 1 image, 2 images, 3 images etc and then use Conditional fields to link this to display and hide the image fields.