Video integration is not yet supported in GG. I am told that using the OmniCore LUA extension that you can display video over the top (using the windows player),
We've been told that video integration is coming, but no idea when. For now your story either needs to be written text, or sounds which can be triggered through the trigger zones, or by player distance from and object or character.
Good Luck
"THERE IS NO SPOON"
AMD 6300 6 core 3.5 ghz, Windows 8.1, 8GB ram, GTX 650 2GB ram