I've always been taught that when frying anything at all, it's of the utmost importance keep the oil below its smoke point. Once the oil starts smoking, I've heard, it's game over-- the oil is denatured and everything in it will have its flavor ruined. And, from limited experience pan frying and deep frying things (I'm still working on the basics), I've seen that this is true. Once the temperature climbs too high, the oil starts to stink and the food ends up tasting like rancid oil.
But, when I watch stir-fry video tutorials, there's almost always smoke. Not just a little bit, either-- it looks like they're thoroughly burning their oil. For example, here's Chef Hiroyuki Terada making chicken fried rice: https://www.youtube.com/watch?v=UzbRwICWODk (he adds the oil to his wok at 3:45). I have no doubt that Hiro knows how to make a delicious stir-fry, but would it be better if he didn't let the oil smoke? Is the high temperature more important than the integrity of the oil? Or, am I completely missing something, and the oil isn't being denatured at all?