> a reference to an object or fact that serves as conclusive evidence of a crime or similar act, just short of being caught in flagrante delicto.

If this isn't a smoking gun, I don't know what it.

I think people forget the last part of the definition, though. A Smoking gun is about as close as you get without having objective, non-doctored footage of the act. There's a small chance the gun is a red herring, but it's still suspicious.