Let me state the issue in this way: I use my iPhone as a dash-cam.
There is no expectation of privacy in public--even though many law enforcement officers apparently think otherwise. see Glik v. Cunniffe, 655 F.3d 78 (1st Cir. 2011)--and when you are traveling in a vehicle, you are in public. I simply love suing police departments that attempt to prosecute people for having dash-cams or using their cellular phones to record police officers in public. (My favorite question to ask police officers is "Isn't it true, officer, that YOUR patrol car has a dash-cam that records audio and video?")
Eyewitness testimony is notoriously unreliable, especially in quickly evolving situations where emotions run high (such as a crash), and as a former insurance claims adjuster and current personal injury attorney, I know of many cases in which insurance companies have denied liability because there were no independent witnesses to a crash.
I expect that cars will come factory-equipped with such devices in a few years; furthermore, most crashes occur at intersections, and many of those intersections are camera and/or video monitored.
Can another party use such information against you? Certainly. But almost all evidence is a double-edged sword and can cut both ways. If you are at-fault in a crash, and the other side doesn't ask for that evidence during discovery, then shame on them. You have no obligation to volunteer adverse evidence or make the other side's case. If, however, you destroy such evidence, you can be liable for a spoliation claim, meaning that the judge can order the jury to presume the video was adverse to your case.
As with anything else in life, you must look at the risks and make your own choices. Life is, as Justice Learned Hand stated, "The calculus of risk." (Yes, that was his true name. Poor guy.)
Anything's possible, but it seems like the good outweighs the bad. If the camera is discreet and no one knows about it, theoretically it could be kept to yourself, though you could be compelled to provide it if another party knew of it. Likewise, it will protect you from false allegations, by police for example. Considering it would be in your car which would be used on public roads and public places, no one could ever really claim an invasion of privacy (except maybe other passengers in your car who don't know their voice is being recorded). As long as your passengers aren't secretly being recorded, it should be okay.
This is not to be considered legal advice nor does an attorney-client relationship exist.
In my view, it cuts both ways. If the dash cam records everything, it can pick up both the driver's negligent acts or omissions as well as other drivers' negligent acts or omissions. My understanding from having watched the coverage of the Chelyabinsk meteor is that the practice of installing webcams in cars is widespread in Russia because of the prevalence there of fraudulent claims. If you are expecting to be slammed into by someone who does so intentionally so they can sue you, it's understandable that you would want to protect yourself.
I think webcam footage is likely to protect a cautious and prudent motorist, and will come back to bite a careless or reckless motorist. Don't record your passengers' conversations without their knowledge, as it is likely to violate the federal wiretapping law.
Not legal advice as I don't practice law in Florida. It's just my two cents on the facts you describe in light of general principles of law. If you need legal advice, please consult a lawyer who holds Florida licensure. That's not me as I practice in Vermont ONLY.
Recording audio in Florida without consent is a felony.
Dash cam evidence will be discoverable in court (you will be compelled to provide a copy to the opposition), and probably admissible in evidence. So the evidence you are creating will cut both ways. The analysis is the same as a retail stores' survelliance video.
This is a summary based on incomplete facts. You should not rely on it as legal advise. No attorney-client relationship is intended to be formed. You may call me 772-562-4570; email me firstname.lastname@example.org, or visit my website http://www.millerlawoffices.us