The game Scrabble consists of tiles with letters on them, and the letters are worth varying amounts of points. Qs and Zs are worth 10 each.
The brother is "kibbitzing" (look that up if you have to) by randomly saying obscure words that are allowed in Scrabble, without paying any attention to the game.
It's unrelated to the television show -- that he was watching the show just shows how little he was participating in the game.
Student or Learner