Just for the record, the reason I showed that video was because I don't believe a properly spined arrow flexes nearly as much...and it is clear that one is extremely underspined as it not only resulted in a failure, but as mentioned...the archer anticipated it happening which is why his hand is covered.
I have seen some other videos of more appropriately spined arrows but I can't seem to find them at the moment. While they all will flex some, a properly spined arrow won't flex near that much. I think Black Widow produced one such video, but I don't have it on hand.
The arrow doesn't spin from helical fletching until AFTER it clears the string...and even then it would take a few feet for the air resistance on the "propeller" of a helical fletch to take effect. For this reason, I fletch arrows so the feathers are arranged at...
For right handed shooters... 12:30 / 4:30 / *8:30
and
For left handed shooters... 11:30 / *3:30 / 7:30
The * being the cock feather, which would be cock feather out. Let's remind ourselves what "cock" feather actually means? Does it only mean a feather that is a different color? If that is the case, then of course it would not matter which one was the ODD color. What does matter, at least in my opinion and experience, is the feathers orientation to the bow (more specifically the arrow rest). I want to maximize clearance and stability...and the fletch (even with a low profile quil and soft feather) does stick up higher than the shaft, so I like it to have a troth "fletching channel" to run through as it clears the bow. I feel this puts me in as good a position as possible without sacrificing anything.