What is the guy in green showing to the F/A-18E pilot before catapult launch? In the following frames, you can see a guy in green showing a panel-like device with numbers on it to the pilot of the Super-Hornet that is about to launch from the carrier USS John C. Stennis. 


What is this panel for? 
What information is the pilot given?
Why just before takeoff and not while boarding/briefing?


(YouTube)

Edit:
I won't accept this question as a duplicate. It may contain the answer 


  Taxiing up to the catapult, a green shirt will hold up the weight board. If the weight on the board matches the weight on the weight chit, acknowledge ...


but the question isn't really about that part and quite "hidden".
That's a weight check. The sign has the weight of the aircraft in pounds. The catapult crew guy first shows the presumed weight to the PIC who must give a thumbs up, agreeing, "Yes, that is the weight I believe my aircraft to have."

The crew guy must then show the same exact set of numbers to the catapult chief operator, who must also approve it: "Yes, the catapult is set to launch that weight.

You can actually see both verifications happening in the two photographs above, the first one is to the PIC, the second to the catapult operator. Only when both verifications have occurred will a launch be permitted.