Olympic weightlifting bars are used frequently at olympic lifting gyms, Crossfit boxes, the Olympic Games or anywhere that lifters may be doing the olympic lifts (snatch or clean-and-jerk). They are made to be springly at high loads to facilitate explosiveness, prevent a high shock load for the lifter, and absorb the shock of being dropped. The tensile strength (PSI) tends to be lower than powerlifting bars so that it isn't too stiff, but newer manufacturing methods are resulting in some very high tensile strength bars that remain springy.
When I see videos like this, I'm amazed by the strength displayed by kids at such a young age.
But what about the detractors? Do kids stunt their growth by lifting heavy weights too early? Does it damage their growth plates? Are they putting themselves at risk of injury, causing them to be crippled as they grow older? Or is weight training a reasonable part of exercise that they should learn at some point?