Blue Order

You can use lethal force in any state if you have a reasonable belief that there is an imminent threat to your life.

The difference between your state and certain other states is that in those states, you have a duty to retreat if you can. This means that in those states, if it is possible for you to retreat without endangering yourself, you must retreat. If it is not possible for you to retreat without endangering yourself, you may defend yourself.

In the case of this video, if the law in NY is that there is a duty to retreat (just a hypothetical, I don't know what the rule in NY is offhand), then the cyclist would have had to retreat from the conflict, unless retreat was impossible (e.g. unless he was cornered), or unless retreat would have endangered him (e.g., unless retreat would have exposed him to certain attack). In Florida, on the other hand (I'll accept what you're saying as fact, although I haven't researched Florida law), the cyclist would be allowed to stand his ground, even if it means a certainty that the other guy would attack him.

This raises an interesting issue-- actions that constitute self-defense in one state may constitute mutual combat in another state. For cyclists whose own states grant wide latitude in self-defense, it's important to know what the law is when riding through other states.