Earlier quoted context omitted.
even then there probably should be some minimum "flash" time in that if it turns on and off faster than the LED lights up or human eyes can see then it may still take images faster than we can register? EDIT: a commenter below said "Macs newer than 4 or so years also have a feature that forces the LED to stay lit for at least 3 seconds after it has been turned on to prevent the single-frame-grab attack."
Frankly, by the time the indicator is noticed, it may be too late. Even with the LED wired in place and a 'feature' (capacitor or software?) forcing it to stay lit for 3 seconds, the damage may be done. It does, at least, let you know an attack occurred. I really think an LED is barking up the wrong tree. A built-in hardware cover would have the same effect as the LED, and no one would have to trust it, since the cam…
https://www.youtube.com/watch?v=IKY3hvYKPpA
Too bad it mainly shows your nostrils :(