Oly lifts are terrifying to look at, but assuming you have proper training most of these lifts are pretty safe as there are usually plenty of ways to "fail safely". I don't do oly lifts, but on occasion do power cleans to get into position to do overhead presses without a rack. That tends to terrify people around me too

Power clean is similar to the first part of the clean and jerk (where he pulls the bar explosively upwards and catches it), but in power clean you drive the bar further up into a near jump, and catch the bar much higher up (in a clean you drop down pretty much in squat position when catching).

In clean type movements you can generally fail by pushing yourself and the bar apart so the bar crashes to the floor. Similarly when putting a bar overhead - your main priority is to ensure the bar clears your head, and frankly that's not all that hard as no matter what grip you use, making the bar clear your hands is likely to get it mostly clear of your head.

My scariest experience - once in 10 years of doing power cleans into press position to do my overhead presses - was on a 1RM attempt where I started feeling dizzy halfway into my press, and felt I had to ditch the bar. Even then, worrying I'd faint, it took just a little nudge to get the bar far enough out from me to crash to the ground without touching me. Only caveat was that my fingers didn't clear totally, so I was pulled down after it and ended up dazed and confused on floor, hands still on the bar, but unhurt other than some slight bruises.

I've failed to complete part of the movement (usually the press at the end - you can usually power clean much more than you'll be able to overhead press) many times, but usually you'll know when it's not going to work and can maintain enough rigidity to put the bar down in a controlled way.

It is dangerous, but also rather safe if done properly, just like say driving (which still kills as many people as 9/11 every month in the US alone, you'd think national security budgets would fund driverless cars... well they do, but more than now).

But yeah there've been some really tragic accidents. If you put your hand on the bottom of your neck and you feel your spine, some people have dropped the bar on there and couldn't walk for the rest of their lives. Which is why there's quite a bit of hate for Crossfit from the oly/powerlifting community because a substantial portion of their activity isn't safe. (where at times, either the exercises, or the guidance are inadequate for safety).

Generally though it's pretty easy to move the bar/body when you fail in the movement, and a proper trainer would let you go through those movements first so you get a feel of how to 'escape' a failed lift. The only danger is if you're inexperienced with this, or if you weren't watching your breathing properly and faint during the exercise. (that kind of training/experience is usually extremely solid if you do olympic lifting or powerlifting under guidance. You'll be hard pressed to find an olympic weightlifting trainer who doesn't know what he's talking about. Crossfit hasn't matured as much and there's just too many trainers out there who are novice lifters and teach lifting, and focus on ridiculous amount of volume, and it's dangerous)

I thought I remember reading that lifting can hurt young, growing bones but I would also imagine this kid's couches and parents are educated on it.