It's a unique situation where the driver is not only a witness to a capital offence but also the alleged perpetrator, and the victim was in his car.
Please note that it's an offence to witness, but not report a crime. So Abang did the right thing by immediately conveying the victim of the kidnapping to a police station.
As for the recording, the quick thinking driver had every reason to disregard LTA's rules as he was witness to an alleged crime and was gathering irrefutable evidence of that crime. It's no different from a soldier recording a kidnap taking place in a secret military installation camp even though photo and video taking is forbidden. The soldier will not be punished. In fact, he will probably received a Soldier of the Month Award along with some NTUC vouchers.