The guy in the blue ends up losing the match. So when its over, its time for the mutual respect handshake which is so important in any martial arts event.
It signifies that even though you fought against one another, in the end, it is a competition and keeping in the spirit of true martial arts, you respect one another. The guy in the blue refused to shake hands, and probably muttered some not-so-nice language to the winner. Well, the guy in white thought it was important to teach the sore loser a lesson, and maybe give him a second chance to pick himself off from the mat and shake hands!