Check out some videos of JJu (the other zerg player in this video). He's known for doing neckrolls after beating people. That's why Savior did it in this case.
i think they probably just go down the ladder in their pro gaming team...i'm not exactly sure how they work it though...just a guess...maybe they'd choose to go to a different team that might think he has potential just isn't reaching it with the team he has? /shrug
fro guys who say there isnt a ceremony savior twists his head in circles after winning which is imitation of his opponent usual habit hard to notice i agree and not that impressive but savior hardly does a ceremony so i guess people tend to consider this as a ceremony