Full Screen Viewing

Whenever I select full screen viewing nothing happens ...? Any ideas why it's not activating?

Thanks,
LD Thompson

you need to do 2 things:

first define where you want to view (View menu > Video Playback > choose from the list ... Digital Cinema Desktop Preview - Main perhaps)
then choose to view it (View > External Video > All Frames ... toggle on/off with Cmd-F12)