I look at it this way:
If I were one of the victims which was hit & run by the Mercedes, I would be very grateful for the motorcyclist effort to tail (not chase) the culprit till the cops appeared. If the driver managed to get away and cops couldn't find him, and say you were hurt because of the hit & run, how would you feel knowing the guy got away?
The motorcyclist didn't try to take matters into his own hands by confronting the driver, either trying to physically get him to stop or not continue to drive away, he just followed the guy until the he finally stopped or the car couldn't move anymore. Even then he didn't try to get near to the guy, open his car door, etc. I feel he was smart because the driver could be some criminal, might have firearm.
Sure the motorcyclist did run a few lights, but he didn't do it without looking first to make sure it's safe to run the light, unlike some cops which flip the sirens and blaze through intersections that can be dangerous if you didn't notice them coming by.
In my country we do have cases of drivers hit & run on motorcyclist, some of them are my friends, it really pisses me off that drivers can be so selfish and worry more instead of having to pay damages/insurance claims for a crash they caused. The world is indeed a shitty place and it's just getting worst.
In summary, if it was me in that situation, I'd do the same, regardless if I had a camera running or not. I would tail the a**hole and call the cops to bust his a** since I don't have a bluetooth headset to link my phone to call and ride at the same time.
The motorcyclist has my thumbs up for the effort not letting these hit & run f***holes escape.