[abrasive]

The video's graphic is a bit of an approximation. In practice it appears that every second disc sector is displaced, IIRC. And they've got particular bit patterns written into them to produce a visual logo; these patterns (but not the actual logos) are checked too.

The protection ring is visible to the naked eye for this reason. I can't find a picture, sorry!

[0xcde4c3db]

I tried to figure out how to reproduce the logo at one point (10+ years ago, when people were less worried about dying drives). IIRC, it's that the EFM patterns used to make the pixels don't make valid Red/Yellow Book sector contents, which causes some weird behavior if you try to read them as such.