Theoretically, if the bubble was clearly marked but not fully filled (maybe a checkmark instead of filling the bubble), the human looking at the ballot could make the intention of the voter more clear by filling in the rest of the bubble.

EDIT: I actually found another post that attempts to explain it here.

There was a woman in the longer video that is copying things from a ballot on the left onto a ballot on the right.

If that's what's happening, though, it is still insanely rife for exploit. This is scary, scary stuff.

Theoretically, if the bubble was clearly marked but not fully filled (maybe a checkmark instead of filling the bubble), the human looking at the ballot could make the intention of the voter more clear by filling in the rest of the bubble.

That's about all I can come up with. I'm genuinely curious about what is done in situations like that.

I would assume if there is altering of ballots for the purpose of making them more machine readable, though, there should be a record of what the ballot looked like before and after altering, to prove that it wasn't changing the vote. Since it seems impossible to feasibly do that on a large scale, I've always assumed that altering ballots in any way is completely forbidden.

I'd love to see someone who has worked as an election judge weigh in on this.