The Neurology of Obsession

From the Youtube byline:

I found the Mad Dribbler on Fifth Avenue, not far from the Metropolitan Museum. This is not a performance. It is a genuine obsessive undertaking. Note the green rubber gloves. Halfway through closeups begin. Watch to the end for the best parts, including reactions of passersby. Who is he? Where is he now?

The head movements, more apparent during the close-up shots, look like drug-induced dyskinesias, and provide a possible explanation for the obsessive dribbling.