Clear cut case of self defense.
The guy shot in the arm clearly had a gun and was standing over him- self defense- check. The guy with the skateboard was beating the 17 year old prior to the shooting- self defense - check. The first victim was seen chasing after the kid, and throwing things at him. The actual shooting was not captured clearly, but based on the other circumstances, I’d say self-defense is a pretty good call. The only problem is that it will be years before the case finally comes to trial, and the defense in this case will be expensive.