To my eyes, this is a stock-standard media beat-up story. Everybody is playing their respective roles to the letter.
The television news are promoting the dramatic angle of a threat to our innocent and a citizen standing up for his children, all the while milking* a story that has an opportunity to show teenage girls, which rates well. (* They are revisiting an earlier story, because there is a new report, which they largely ignore for all but a few seconds, to focus on the teenagers.)
The M.D., Dr. Laszlo Mechtler from the Dent Neurologic Institute, calmly (I would say "patiently", but a hint of impatience seems to be coming through!) explains that there is no mystery. His patients have been diagnosed with cases of a Conversion Disorder, (formerly known as "hysteria"). It rarely appears as "mass hysteria", but it is a known condition, especially amongst impressionable females.
The Brook Dupont's father (perhaps because of the stigma associated with mental illness or perhaps because he doesn't understand that the diagnosis is not suggesting that they are faking it, is not suggesting are not suffering and is not suggesting that they all got sick together "by coincidence",) hasn't accepted that answer, and seems to be criticising the school.
The girls, perhaps coached, are demanding answers, "straight answers". A strange request that seems to assume that illness is something that is assigned to people by elected officials who have to respond to their public for their decisions. It also ignores that their doctor has given the press a straight answer, and presumably them too.
The school, being an innocent party coming under fire, have retreated, and paid for independent inspectors, in what appears to be an attempt to defend against criticism and cover their backs. The inspectors conclude, exactly as the doctor's diagnosis would have predicted, there is no environmental issues at the school.
The school's statement, excerpted by the reporter, says they consider "that the symptoms are real." This is perfectly in keeping with the school accepting the psychogenic diagnosis, and them trying establish that they don't consider such symptoms as being "made up" or any less debilitating for being a mental, rather than a physical, issue.
So, just by watching the report, and listening to the actual experts quoted, we see that it is not an school-based environmental issue, and that it is a diagnosed case of a rare, but known mental disorder, Mass Hysteria (or Mass Psychogenic Illness, if you prefer).
@KonradRudolph has identified a recent article in Nature News that claims the outbreak "confounds experts". Unfortunately, it fails to name who those experts are. It claims "the LeRoy situation doesn’t fit the diagnosis very well, say sceptics", without explaining who those skeptics are or how they sourced their information.
Meanwhile, an earlier article in the Buffalo News actually interviews many of the experts involved in the case:
But the many physicians who have consulted, examined, tested and diagnosed these students -- rendering first, second and third opinions -- don't think the disease is a mystery at all. And they aren't baffled.
They've come to the same conclusion: These students suffer from a real physical condition that has an underlying psychological cause. Individually, they suffer from conversion disorder, and collectively, they suffer from mass psychogenic illness, also commonly referred to as mass hysteria.
It goes on to explain how the matter was escalated, with different levels of the health system being consulted, and extensive tests run.
To be fair, there is one doctor who disagrees:
A number of them are having their children evaluated this weekend by Dr. Rosario Trifiletti, a New Jersey-based child neurologist in private practice, and the only physician to have publicly disputed the conversion disorder diagnosis as "garbage" on WGRZ-TV.
Dr Trifiletti is an expert in a controversial maybe-disease PANDAS, and suspects that this is the cause. The legitimacy of PANDAS as a diagnosis would probably make an excellent separate Skeptics.SE question.
The school continues to be under fire, trying to manage the levels of speculation, misinformation and even trespassing of the local and national media.
Discover Magazine has an article
by Dr Vaughan Bell
that elaborates further about the disease that has been diagnosed.