It's not a scam in the fact that the cruise does exist. However it's a scam in the fact that flight is not included and that it's not 10% of the actual value. It's more like... 95-100%. The cruise is probably worth the $400 "registration fee".
It's also a scam in the fact that your brother didn't "win" it. Basically they call every number out of those who entered the "contest" and tell them they've won. It's all really just a really crappy way of getting you to watch a 2-hour presentation on time shares.
Here's a link below regarding the scam:
http://boakes.org/ameri-scam/comment-page-66/