The more I read about this accident, the clearer the picture emerges. IMHO, both teams of controllers from Teterboro and Newark may have inadvertently contributed to the accident - they had grown complacent to the multiple collision alerts which have become background noise in that busy corridor. I believe the FAA has a lot to answer for too, due to the lack of separation minima between FW and RW aircraft over the Hudson.
In this incident, nobody wants to be a scapegoat, but the reality is that the cheese holes have been lining up one by one over the years.
I feel very sorry for the pilots (and their pax) who paid the highest price in order to progress this learning exercise. Judging from the video, neither saw each other and probably neither could have seen each other in the circumstances.
Just my humble 2 cents worth.