There was no reason for him to climb into IMC in the clouds. He had no instrument rating and he hadn't filed. By all accounts he was experienced flying VFR around NYC, and probably had experience flying low-level VFR (scud running) along the East River and over the harbor...it's what we can legally do in rotorcraft. A typical scenario in low ceiling/vis would be depart the heliport to take a look, fly low and slow down the river and if things look too crappy make a 180 and retrace the route back up to the heliport and call it a day. Why would any experienced pilot climb into the ceiling and then make a near-vertical dive? He did a lot of erratic, inexplicable maneuvering during this brief flight...especially turning west INTO downtown Manhattan. The East River is a big ole landmark that would have led him right back to the heliport.