Well, that plugin indeed places those bars to indicate that only what is not covered by the grey bars is going to be exported. I usually use it only in a copy of the file.
It is not very easy to use this plugin with renderers. Some of them does not export the exact SU cameras as they are exported from SU itself. Without further tweaking of the camera settings, I have only had success with Twilight so far (but then of course I have not tried every rendering engines yet).
Most (or at least many) renderers have panoramic (360d) export options however. They are neat but this usually needs much system memory (to create an acceptably large panorama - note that you usually only see about 1/4 of the image while the rest is "behind you").