Sorry, but the policeman was doing his job exactly the way he had been trained to do it.
When a policeman is conducting an investigation no outsider has the right to get involved. In this case, the policeman was speaking to a driver, the cameraman should not have gotten invloved. Any third party distrtaction can be interpreted as interference with a police investigation, including any form of verbal harrassment directed at the oficer.
You do not have to be guilty of a crime to get arrested. The police have a legal right to detain you on suspicion alone. The law provides them with 72 hours. They can detain you for 3 days, not including weekends or holidays, to investigate whether or not you have violated any law.
The lesson to be learned: When a police officer is in the act of performing his duty, do not even attempt to speak with the officer unless you have a legitimate emergency requiring his help or assistance. This is the law.
Footnote: Since 9/11, most states have upgraded "police or fire interference" to felony status.