Fairly sure there isn't even a 100ppi image of my fingerprint anyone can gather, let alone one that is 2100ppi. Secondly, the video doesn't show full navigation into the enrollment process (well enough for my liking).
What do the screens look like when adding an additional finger, versus what is shown? (sorry I don't have a 5s, and the display demo at the stores don't show normal TouchID preferences.) . Is there any way to confirm that his middle finger was not previously enrolled?
Good luck obtaining that from my phone
A) I have a case that is highly difficult to get fingerprints off of (material is not smooth)
B) I would register a finger I never use holding the phone, nor in normal operation of the touch interface

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C) on the given finger I would register, I would only register a portion of that digit, that normally wouldn't come into contact with my Phone (or anything else I am holding). You can (it takes some effort) only register part of your finger. the Software makes it hard, but you can get away with registering only one side of your fingerprint if you choose to do so.
That said, Most people won't think outside of the box, and will go with the easiest way to unlock their phones. I will (when I get a 5S, or 6), likely keep my complex passcodes, and use a partial fingerprint for TouchID.