The man in your video Xfean says it must be a violent forcible felony. That appears to be the case.
"A person who is not engaged in an unlawful activity and who is attacked in any other place where he or she has a right to be has no duty to retreat and has the right to stand his or her ground and meet force with force, including deadly force if he or she reasonably believes it is necessary to do so to prevent death or great bodily harm to himself or herself or another or to prevent the commission of a forcible felony."
The key word here that you are missing is PREVENT. No where does the law state that you have to have life threatening injuries...
Zimmerman is justified by the law.
He was only arrested to appease certain loudmouth racists in society.