Make a new modal ExtJS window, with a disclaimer text in it:
"Attention: For all currently selected projects and tasks the Visual Content is updated with the here uploaded PDF document"
"Achtung: In allen ausgewählten Projekten und Aufgaben wird der visuelle Inhalt mit dem Inhalt der PDF aktualisiert"

Adopt "Batch set properties" window with a file upload in the center and a security question

Menu labels:
Batch operations = Batch-Operationen
Visual Review PDF aktualisieren = Exchange Visual Review PDF