Before moving this to Script Requests, I thought I'd leave it here for a while because I'm wondering if there is an evented solution to this. Would you be happy with doing this by events, or do you specifically want a script to do it? However, a bit more detail would help. Is this a video at the beginning of the game only, or do you have videos at different points? Also I know some people occasionally refer to cut scenes as videos. These are definitely videos and not cut scenes?
I would have thought you could make this as simple or as complex as you like. For example, before the video you could have a dialogue asking the player if they want to view it. Then a conditional branch. If they say Yes, show the video. If they choose No, then move things forward to a point after the video e.g. a new page on the event.