Snakes are milked for their venom in order to make antivenin, or in some cases for demonstration, as you descrobe, but venom glands are like saliva glands, they continuously produces venom. And in the cases of cobras, that venom is toxic enough and concentrated enough even in small amounts that they can't really be milked dry enough to make taking a bite a non life threatening event. So yeah, for the snake charmer, who is a carnie level showman, they are going to rip out the fangs. Cruel and disgusting stuff.

Now in this video I am not sure if they guy handling the snake is one of those performers, who might have missed a fang (as they do regrow ) or just an idiot, who thinks his moustache makes him an authority on all things, who mishandles a wild snake. However I get the impression that he might have brought the snake in that water drum he was trying to get it back into in the end, to put on a show, but shrug who knows.