The meaning is contextual.
Exactly: and it says “official trailer” — separated from the rest by a fancy hyphen just like what I have used. The context is quite clear that it’s the trailer that’s official, and thus the meaning is quite clear as well.
The context is the ‘Portal’ game series by Valve. Interesting how you conveniently skip right over that part.
The developer has now changed the video and removed the word ‘official’ from the title. The video also includes the text ‘Portal: Revolution is an unofficial, fan-made modification for Portal 2 and is not with or endorsed by Valve Software.’ If there was no issues with saying ‘official’ then why did they remove it and add that text there?