My opinions, and the justifaction for them are as follows:
You might be legally allowed to shoot. New York law allows a person (not just a police officer) to use deadly physical force to prevent a forcible kidnapping.
It is reasonable to assume that the life of a person being forcably kidnapped is in danger. The only two reasons I can think of to forceably kidnap someone is in order to commit a subsequent crime to them, which may include rape or murder; or to ransom them, which often times leads to the victim being killed either way.
It is still not a good idea to start shooting. 1) It may not be a kidnapping. The situation on the video looks pretty unambiguous, it looks like a kidnapping, but it wasn't. New York law allows you to use deadly physical force to prevent a kidnapping, but you are vulnerable to prosecution if you use deadly physical force to stop what you mistakenly thought was a kidnapping. In other circumstances, what you think is a kidnapping might be a parent dragging their bratty child home, a cop making and arrest, another kind of gag, etc.. 2) Shooting may endanger the victim. They may not be in any more danger than if they were sucessfully kidnapped (you hit them accidently, or the kidnappers shoot them on their way out), but they might be in more danger than if you shouted to scare of the kidnappers, or called 911 with the location, direction, and description of the kidnappers. 3) The odds are not in your favor. There's only one of you, and more than one of them. 4) You can't call 911 if you are dead. 5) You are likely not equiped (physically and from a training standpoint) to detain the kidnappers, so the best you can hope for is for them to get scared and run off, there are probably better ways to do that, like maybe by yelling, "Get out of here, I just called the cops and gave them your plate number" (extra points if you really did). 6) A real kidnapping of an adult has to happen fast, and once the bad guys get into their vehicle, it's over (you shouldn't shoot at the vehicle, and you probably) aren't going to stop them from leaving. By the time you can react, be sure what's going on, and draw, it's going to be over. 7) Again, it's not you job to intervene. As such, you do not have the gear, the back up, or the legal protections and authority you need to intervene effectively in such a kidnapping. Note: I agree that if the victim was someone you knew well, some of the above would change, and I can envision circumstances where shooting might be appropriate, but in my case, I also know those situations just aren't going to occur.