Via Allah's twitter
This is not a real professional baseball game.
There is a fund-raising baseball game organized by actors, musicians, television stars and other public figures annually and they were trying to entertain the crowd.
The game they are playing can be roughly translated into "chicken fight" which is a traditional Korean game where the players hold one of their leg up in the air and try to knock each other out.
I hope that cleared some confusions around here. By the way, baseball in South Korea is extremely popular. Aside from US and Japan, I am pretty sure South Korea has one of the largest baseball fan base in the world.