Looks like a calibration issue. They should have included selecting other candidates in the list. While not good enough (voting machines should be "perfect") calling it "altering votes" is a little much. It shows you that it has registered the wrong candidate, I would call this incorrectly registering input.
"I first thought the calibration was off and tried selecting Jill Stein to actually highlight Obama. Nope. Jill Stein was selected just fine. Next I deselected her and started at the top of Romney’s name and started tapping very closely together to find the ‘active areas’. From the top of Romney’s button down to the bottom of the black checkbox beside Obama’s name was all active for Romney. From the bottom of that same checkbox to the bottom of the Obama button (basically a small white sliver) is what let me choose Obama. Stein’s button was fine. All other buttons worked fine."
FWIW:
Using a cell phone to take video in polling places in most states is prohibited, and in general "frowned upon" in others. I would not be surprised if he simply took a video as quickly as he could and then left. I agree it would have been a more believable incident if there was more video.
Based on the reddit story, I think this was Central PA, which definitely falls into the "not allowed to take video" category.
