According to an Evangelical christian and herpetology enthusiast I know online, the "Holiness" Pentacostals engage in a LOT of theatrics-
They apparently milk the poison from the snakes before their meetings, and will do other things (like manipulate temperature) to keep the snakes relatively slow and docile.
Seems to make sense to me, as any of the footage I have seen, the snakes don't look terribly agitated, even though they are being tossed around.