I was watching this on live tv. Dallas Marathon is delaying posting the video. If they get around to it I'll post it here. If they don't post it for whatever reason, I've got it narrowed down to 4 people and will be able to confirm once pictures are posted.
At the Dallas Marathon, like many other marathons, they have different colored bibs for all the events. Like every race out there you can see the course beforehand. There are plenty of signs and people directing the way.
The women's leader, Shitaye Gemeshu, had a huge lead for a majority of the race. There wasn't another woman in sight for most of the race after mile 8. As Shitaye is coming into the finish chute there is this lady in a half-marathon bib breaking out into a fullsprint. It takes Shitaye by surprise so she doesn't speed in time. This hobby-jogger is frantically trying to get ahead of the full marathon finisher and barely does by a half second or so. She breaks the tape, stealing the banner moment from Shitaye. Unbelievable.
I've run this course before. It's very unlikey this was just a confused half marathoner who found herself in the full marathon. For the last 2 miles or so, the half and the full are on the same street but on opposite sides of a street that's divided by a median. Furthermore, how could she possibly think a 2:46:46 half marathon is a winning time?
To end up in the Full chute this half-marathon hobby-jogger would have had to step up on the median at some point in the last 2 miles and go to the other side of the street to be able to get into the full chute.
Editor's note: Here is an article from the Dallas paper about it.