I've created 2 test applications:
In the one the documents are included into the bundle and can be opened by using the quick look controller. In the other app, the documents are downloaded. When I try to open the files the quick-look controller simply shows a message saying an error occurred. Strangely it will open downloaded PDF documents without any problems.
I suspect it has something to do with headers and mime-types, but I'm not sure on this. Would anyone know what the reason could be that downloaded .doc or .docx documents won't open and local documents will?