Voters were given a plastic stylus and told it would mark their ballot with "invisible ink"--obviously their blank votes wouldn't count.
A representative from the Chicago Board of Elections told the reporter, with a straight face, that there was not malicious intent, but rather, "we are convinced that it was just utter stupidity."
Of course it was. What we're not told, though, is the political party or race of the voters and precinct workers. Given that this occurred in Chicago, and working on my assumption that the "utter stupidity" rationale is, itself, utter stupidity, wouldn't those few tidbits of information seem to be rather important?
Update, 2/6/08: In case the video link goes away, here's a Chicago Tribune link (free registration required, hat tip to NewsAlert).