In this video of a chef deep frying shrimp, he repeatedly applies more batter to the shrimp, clearly touching the oil over and over. Does the batter protect your fingers? Is it just a short enough time to not be burned? It seems like this shouldn't be possible in oil hot enough to cook meat. Is this a safe practice?
Mostly, experience with working with frying oil.
And a bit of science:
The cook probably has his hand wet, and when he touches the oil, the heat from the oil forms a thin steam barrier between his hand and the oil.
See this related video about dipping a hand in molten lead.