It is extremely difficult to help someone with their LabVIEW code when we can't look at the LabVIEW code. It appears, from your description, that you use LabVIEW to start VLC, then use LabVIEW to maximize the VLC window (which allows you to manipulate its User Interface and take pictures), then minimize the window (which hides VLC's User Interface).
It would be helpful to actually see if this "guess" is what you are doing, or if you are doing something else that may suggest a way you can accomplish your task. Otherwise, if we have only a vague idea what you are trying to do (and how you are trying to do it), we can only give you a vague answer for why it isn't working.
Post your LabVIEW code.
BS
