There's no way that those died due to an airflow issue, especially with those two 80mm fans, like Kougar mentioned. I know the guys who did that video and they take things seriously, so I don't think they'd overlook something so simple. What's amazing to me, is that all six died within two minutes of being at 75% load... that's nuts!
Corsair does make some great PSUs though (which is why we have a 1KW of theirs in our main rig), so I guess they have all the reason in the world to point these facts out to people.
As for PSUs that have died, I've killed a few in the past, but that was mostly before I began to take things seriously and "got a clue" so to speak. The worst hardware-related incident I had with a new product was with BFG's 6800 GT PCI-E. This particular card was the third I got back from RMA (yes, these cards were crap), and on the first boot, it sparked up and killed itself and also my monitor. Was not a good day.