How do you know that this would "never happen in your pocket or under normal use"?
Of course the iPhone will not bend in your front pocket as much as if you bend it with your hands. But if you can bend it as easily as shown with your hands if you put pressure near the volume buttons, its probably possible that the phone could also bend in your pocket under certain circumstances (jeans size, position of the phone in your pocket, time of pressure put on the "weak spot") and of course to a way lesser (=minimal) but noticable (if you put it on a table e.g.) extent...
Again, if the metal reinforcement behind the volume buttons would be longer, it would also be harder to deform it as shown. That's not "poor design"? And just to make it clear, I'm everything but an Apple "hater" (instead Apple user since more than 12 years), but I'm not blind too.
You took one guy's HYPOTHESIS, and assume it to be absolute truth. A poorly explained hypothesis at that, especially concerning his A & B shapes.
While I can understand what he is trying to say, I'd also like to point out that that design of internal reinforcements, interrupted by breaks, continues all the way down the side of the phone. And if I had to guess, it also lines the opposite side of the phone. Please also note that the battery flanks that entire length.
While it is POSSIBLE that his explanation is the cause, it is certainly far from the truth.
It is far more likely that the breaks are the weak points since they are not reinforced there, but reinforced on the two immediate sides. However, you have to note, that you have the same break roughly midway down the phone (use the SIM tray for reference), precisely where the consumer reports testing, and Apple's testing applies their force. And Apple's is applied over a smaller surface area longitudinally compared to his thumbs, with 90 degree edges as opposed to this thumbs. If there was a bending problem due to the breaks or the reinforcements, we would have seen the same type of bending from the Apple/CR testing.
I am not saying the phone can't bend, or that the reinforcements aren't the cause. But if they are, there are more breaks than just the one below the volume buttons.
I just can't imagine those forces being generated on your phone, at that precise spot, by your jeans. Unless you were wearing EXTREMELY tight jeans, I just don't see it happening in normal use. Can it happen? Possibly. But not in normal use.
I'm willing to bet that the increase in reports are coming from people now trying to purposely bend the phone after watching these videos.
Anyone remember the iphone 5/5s bending claims? A few people had the same problem. It was actually in the SAME PLACE (just below the volume buttons). Doesn't mean it was widespread or a design defect. I used my iPhone 5 normally for 2 years, and never had a bending problem, just like the MILLIONS of other users.
Anyone have a teardown of the 5/5S to compare?