I'm glad he wasn't charged for the shooting, but I'm trying to wrap my brain around why he wasn't charged with unlawful possession of a firearm. I can think of a few possibilities.
1. The prosecutor's office told the grand jury that they were only interested in pursuing a murder charge, or,
2. Even though the video proves he had the gun at least long enough to defend his brother, to prove that he possessed it illegally would require him to testify against himself.
Any other guesses?