The video was only recorded by Pittsburgh's Channel 4. Scott Baker is Channel 4's correspondent on site in Boston. It's unclear if Scott Baker was with the camera operator. Scott Baker is rumored to be quite conservative. He's the ex-husband of the Pittsburgh Post-Gazette's outspokenly conservative columnist Ruth Ann Dailey (and the current husband of a recent ex-Miss America).
The Tribune-Review is a notoriously pro-Bush paper. Given their manner of "reporting" (constant Kerry-bashing, et.c.) Teresa Heinz Kerry is likely not happy with the paper. Both Scott Baker and the WTAE camera operator must know what the Tribune-Review's editorial editor, Colin McNickle, looks like. Heinz Kerry might not have known what Colin McNickle looks like, but she'd surely know his name.
It's possible that Scott Baker had the camera operator "keep rolling" when he saw McNickle start to question Heinz Kerry, or arranged for the columnist to be there.
I started wondering about this this morning. During the afternoon news, Scott Baker, who's normally pretty reserved while reading the news, was almost gleeful as he recounted the "Shove It" incident, nearly 2 days after it happened. As the main reporter at the Democratic National Convention for WTAE, he didn't mention any of last night's speeches one time during the 5pm news. Baker's behavior is reinforcing my notion that he could have helped arrange the incident.
Another Possibility: It later occurred to me that maybe Heinz Kerry herself wanted the incident on camera. When a TV camera is as close to you as it was to her on Sunday, you know it's recording (the lights make this really obvious). So when she learned that Colin McNickle had been talking to her, she went back and made a point of saying what she did in front of the camera. That way, a "shove off" could not become a "fuck off" or something worse because it had been recorded in front of witnesses.