The Accelerated Dragon Variation is a chess variation of the Sicilian Defense.
The drawback is that White must not play 5.Nc3 now (as the e4-pawn is not attacked), but can play 5.c4 instead (this is called the Maróczy Bind) which is uncomfortable to play and leads to a depressed game for Black.For example: 5.c4 Bg7 6.Be3 Nf6 7.Nc3 Ng4 8.Qxg4 Nxd4 9. Qd1 Ne6 10.Rc1.
In the Maróczy Bind 5.c4 Bg7 6.Be3 Nf6 7.Nc3 O-O 8.Be2 d6 9.O-O Bd7 10.Rc1 Nxd4 11.Bxd4 Bc6 12.f3 a5 13.b3 Nd7 Black wants to exchange his Bishop g7 for White's good bishop. White's remaining bishop would then be blocked by his own pawn structure.
Other moves are 5.c4 Bg7 6.Nc2(not 6.Be3), avoiding exchange of chess pieces as Black is restricted in space. (Exchange of pieces would favor Black) 6...d6 7.Be2 Nf6 8.Nc3 O-O 9.O-O Nd7 10.Bd2 Nc5 11.b4 Bxc3 12.Bxc3 Nxe4 13.Bb2 (White sacrifices a pawn)
Usual play (No Maroczy Bind) is 5.Nc3 Bg7 6.Be3 Nf6 7.Be2 0-0 8.0-0 and now 8...d5 in one go (and not d6 and d5 - as in some variations of the dragon, which uses up two moves)
But if White plays 8.Nb3 (not 8.0-0) Black must play 8...d6 and the game transposes into the Classical Dragon.
Bottomline: If you are Black play d5, if you can!
(ex: 7.f3 0-0 8.Qd2 d5! in one go)
If 7.Bc4 0-0 8.Bb3 a5! (threatening a4) 9.f3 d5!
Why did Black lose? He didn't strike back in the center capturing the e-pawn with d5xe4. But he played e6 instead. After that White closed the center playing e5. This stopped Black from getting active counterplay in the center and White just overrun him at the kingside.