Welcome to the forums :)
How do you plan to playback the video? In Quicktime or another application?
Do you have another Mac to playback the video or from the same Mac?
Is it one long video... or multiple videos and each on must sync per "song"?
Also, I might recommend you check out Arkaos which can easily launch video to an external display... In Mainstage you can send a MIDI out note (through the IAC Driver) to trigger the video playback in Arkaos.