Honestly, this wasn't a big surprise for me. I've been working in the computer field long enough to understand how easy it can be to rig an election that uses electronic voting machines once someone finds "THE" weakness in the system. Plus, the now defunct TechTV show "Screen Savers" once had a guest that demonstrated this very same tactic of switching votes from one candidate to another as a way to rig a vote.
Despite its long known flaws (mainly ballot box stuffing), the use of paper ballots physically marked by humans is probably still the most reliable method to tabulate votes during an election. Whatever happens, you always have a physical paper trail that hasn't passed through a machine at any stage.
I found the film to be a bit on the long side. I was waiting for them to get to the point and demonstrate the flaws in the system.