My understanding is for felony murder, there has to be a direct line to the murder. There is no reason for the guy with the camera to anticipate the other two would possess a shotgun, nor anticipate that there could be a tussle for the shotgun that he didn't know existed because the prosecution probably never demonstrated any connection between these people (if they did it was not in the closing statements). There is evidence he may have committed felonies by 'assaulting' him with his vehicle, even though they don't know if he was hit. And going by the detail I saw of their paths, it looked like he was trying to force him in between the two vehicles, and if that is a felony: then he is guilty of that too. So while I think him being found guilty of a felony is reasonable, I don't think felony murder is reasonable. Based on what I know.

The message of that charge is that you can't assist strangers with citizens arrest, because something may go down that is beyond your power to stop it or even know about it and you can go behind bars for life... at least if you're an ugly incel-y looking man.

Remember, the standard should be reasonable doubt and innocent until proven guilty. If you have no factual evidence supporting a connection between these people, you can't assume it. It is the prosecutors duty to counter that with evidence.