The video seemed clear enough, showing an apparently two- sided confrontation that escalated into violence.
A Range Rover collides with one of scores of motorcycles on New York's Henry Hudson Parkway. A confrontation ensues, then another crash in which the Range Rover driver ploughs over the stationary bikers. Finally, a chase that ends with the SUV driver being attacked as his wife and toddler sit helplessly.
But the crispness of the helmet-camera images, captured by a rider in the pack of motorcyclists, gave way on Tuesday to a painstaking effort by investigators to piece together a frantic sequence of events that stretched over many minutes and several kilometres and that involved dozens of suspects and witnesses.
In the end, police decided not to charge the man behind the wheel, Chinese-American banker Alexian Lien, 33.
Instead, police said on Tuesday that they had charged two of the motorcyclists; one of them had turned himself in. A third rider was sent to hospital, according to a family representative, who said the man's legs had been broken when the Range Rover roared through the crowd of motorcyclists gathered around the one who had been knocked to the ground in the initial collision.
Lien - a Columbia University-educated banker with experience at Credit Suisse First Boston and Investcorp Bank - was staying out of sight on Tuesday, even as his confrontation with the motorcyclists became national news and had authorities raising concerns about motorcycle groups that try to take over roads for impromptu races and stunts.
Detectives were looking into the possibility that the motorcyclists involved in Sunday's episode had been trying to clear cars from the road - in an effort to perform tricks and ride unencumbered - when they encountered the Range Rover.
The video appears to show motorcyclists at entrance ramps, possibly in an effort to block vehicles.
Such tactics are not uncommon among large groups of motorcyclists in and around New York, the authorities said.
"We see an increase in the number of groups who will take over the entire highway for the purpose of slowing it down to allow others to race in front of them," said Major Michael Kopy of the New York state police.
The New York City police commissioner, Raymond Kelly, said hundreds of motorcyclists had descended on city streets on Sunday for a planned but unsanctioned event loosely organised by a riders' group called Hollywood Stuntz.
"We had over 200 calls just on Sunday about this particular group operating in a reckless manner," Kelly said.
In interviews, motorcyclists in the group said that as they reached the Henry Hudson Parkway, there were many cars on the road.
But as drivers slowed and pulled to the right to let the motorcyclists pass, the Range Rover remained in the centre lane, the video appears to show. The first crash occurred as a rider slowed to a near-stop in front of the SUV.
The video does not clearly depict the actions of the motorcyclists at that point. But the police said Lien quite likely feared for his safety as he sat in the vehicle with his wife and two-year-old daughter - his car stopped and surrounded.
The man who turned himself in, Allen Edwards, can be seen in the video pounding on the SUV with his hands as another rider smashes the driver's side window with his helmet, the police said. Lien was then dragged from the car and bashed. He had facial lacerations and bruising and has been released from hospital.
Edwards, 42, of Queens, was present when Lien was assaulted, the police said. He was charged with reckless endangerment, criminal mischief and menacing.
The motorcyclist who was arrested, Christopher Cruz, was charged with reckless driving, reckless endangerment, endangering the welfare of a child and menacing.