I don't know the answer to your question but while you have two audio experts GZ has two eyewitnesses he was on the bottom. Here's from a state of Fla. licensing web site.
Q. When can I use my handgun to protect myself?
A. Florida law justifies use of deadly force when you are:
Trying to protect yourself or another person from death or serious bodily harm;
Trying to prevent a forcible felony, such as rape, robbery, burglary or kidnapping.
Using or displaying a handgun in any other circumstances could result in your conviction for crimes such as improper exhibition of a firearm, manslaughter, or worse.
Example of the kind of attack that will not justify defending yourself with deadly force: Two neighbors got into a fight, and one of them tried to hit the other by swinging a garden hose. The neighbor who was being attacked with the hose shot the other in the chest. The court upheld his conviction for aggravated battery with a firearm, because an attack with a garden hose is not the kind of violent assault that justifies responding with deadly force.
Q. What if someone uses threatening language to me so that I am afraid for my life or safety?
A. Verbal threats are not enough to justify the use of deadly force. There must be an overt act by the person which indicates that he immediately intends to carry out the threat. The person threatened must reasonably believe that he will be killed or suffer serious bodily harm if he does not immediately take the life of his adversary.
http://licgweb.doacs.state.fl.us/weapons/self_defense.html