This is a fight between male rat snakes. It's popularly called "combat dance". Each male tries to control the body of the other by twisting around it and tries to keep his own head above that of his opponent. They also try to push each other's head down. The evasive movements of the two snakes results in what looks like a dance, so that people often mistake this to be mating.
Video by: dotcompals
Detailed text provided by: Hari Krishnan
(Palakkad,Kerala, India). More Pictures available at http://www.KeralaClick.com