I've found some issues about windows file names and spaces. With solutions from this forum it's possible to open video files with spaces in file names.

But it's impossible to open files with the windows unc notation like \\server\sharedfolder\resource.avi (wikipedia: http://en.wikipedia.org/wiki/Path_\(computing)#Uniform_Naming_Convention )

What can I do to open Files from UNC paths?

best regards,
  josh.