Here are a couple other videos.



Ok, the first video perhaps a little less professional than the OP's video. However, I have to wonder about the theory from the first post of galvanic corrosion occurring almost uniformly around the crank, rather than primarily around the crank spindle.

Here, the presenter suggests perhaps heat/cooling cycles and hotter parts of the world. Salt and coastal areas, and perhaps a few additional faults. FLORIDA MAN!!!

The last video has some more analysis.

In the middle of the last video, 6:40 to 8 something there is a discussion about 105 vs Ultegra/Dura Ace.

The 105 is "hollow forged" which I believe is the process from the Octalink cranks.

The Ultegra/Dura Ace is "hollow bonded" which is the new process that is failing.

So, if you are racing, perhaps pick up the Dura Ace, and replace at the end of the season. But, if you want to have a bike that lasts for decades, then get the 105.