On: Why Online Voting Is a Danger to Democracy

[Findeton]

Well he should try http://agoravoting.org

[dlitz → Findeton]

How does this guarantee a secret ballot, i.e. that voters remain unable to prove to a third party that they voted in a particular way?

Low-value elections don't necessarily need secret ballots, but it's important for high-value elections, like selecting the POTUS.