See, when I saw "Seatbelt Failure" in the video, I wasn't thinking the car's seatbelt was faulty and suddenly detached and the car manufacturer was to blame. I was thinking the seatbelt unlatched because A--the kid unlatched it himself (this is very common) B--the mom or kid in buckling the seatbelt didn't push it all the way into the holder to make it click and therefore the seatbelt was kinda buckled and technically "failed" because it didn't hold the kid in the seat when the impact jarred it loose. In which case I think that happens fairly frequently as a result of human error not car manufacturers error.
I'm not blaming the mom or the kid in this case, it's a horrible situation to be in. But the point I got from it is a 5 pt harness is very less likely to fail because there's 2 buckles and it would be very difficult for a child or parent to not buckle completely or for a kid to unbuckle himself.
I told you guys I sent this to a bunch of people. I received several comments back.....a few thank yous, one from a friend who had just switched her son to a booster and promptly switched him back. Another friend refused to watch the video entirely.

She said she didn't want to know because she figured the kid got paralyzed or died. She went on to say how they just got back from an 8 hour car ride where her kid, 3 years old, exactly 40 lbs plays a new game and ducks in and out of the seatbelt saying, look I'm not buckled, now I am, now I'm not.

HELLO!!! I set out this email because of you!!! You won't watch it and here you are telling me your kid does dumb things with the seatbelt!!!!

I told her she really needs to watch it.