Text event messages are created using:
Code:
historic_event event_name true factions { england, }
Where true is optional and makes it a yes/no event, and factions is also optional and makes the event only display for the specified factions. To convert this to an event which plays a video, use this instead:
Code:
historic_event event_name event/video_name.bik factions { england, }
Where, again, factions is optional. Make sure you include the video_name.bik file in your mod's data/fmv/event folder.