Most of that show, unfortunately, was just a regurgitation of a broadcast they did a few years ago, though they did dedicate a few minutes toward the end of the program "catching up" with those kids they featured, where/how they're doing now, etc.
They never mention any kind of PANDAs/PANs connection to the OCD, let alone investigate it. When the program first aired, I posted an email to 20/20 via ABC and told them about PANDAs and suggested they investigate it. Never heard a word back.
Interestingly, the research doctor they interviewed, Rosenberg, was interviewed for the original story, also. And both times, he had the results of brain scans (I think they're SPECT scans), and I think he's accessing them via coordination with Dr. Chunagi, who has done some scans of some PANDAS kids here on the forum. In the original story, Rosenberg commented on how he found unusual concentrations of glutamate (neurotransmitter) in the caudate nucleus of the kids with OCD as compared to "normal" kids. Which pricked my interest because Swedo, in a number of her presentations, provides a brain scan of one of her early patients for whom, prior to PEX treatment, the caudate nucleus was "inflamed" or larger than normal.
The "new" research finding that the teasers trumpet have to do with Rosenberg's more recent findings that the type of OCD (say, contamination versus "just right" OCD) can be identified by WHERE in the brain the atypical concentrations of glutamate are found. But the story didn't go into any greater detail, except to say that Rosenberg had just delivered these results in a presentation in New York the preceding week.
I Googled and tried to find a new paper by Rosenberg, but didn't come up with anything.
The story also didn't really go into any depth regarding the treatment(s) these kids have successfully received.