How do you hand-off your game for smooth trailer-production?

Firm Deadline:
"We need this trailer for when it releases on  June 21."

Clear Game Description:
The client explained what the expansion is, what it's key features, and the most attractive selling point (It's free!).

Downloadable Footage:
All of the footage I needed for the trailer was already pre-captured, uploaded, and ready for me to use. This saved infinite time by ensuring that I didn't need to spend any time capturing footage.

Key Messaging:
The client provided the exact phrases to be used as selling-points throughout the piece. The lines were things like, "NEW EPIC WEAPONS!" and "NEW CHALLENGES AND ARENAS!" I modified these slightly, but they were perfect places to start the conversation and get me right into production.

Music and Artwork:
The client providing me with the whole soundtrack, I could easily scan each track and find exactly what I needed to pair up with the key logo artwork and messaging.

Game Copy:
I don't often get a copy of the game when the client provides game footage. This was an impressive professional courtesy in Golaith's case. It ensured that I could tap-into the spirit of the game itself, even if I didn't have the time to fully wrap myself around the experience. It's a generous detail.