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Both parent and GP are wrong.

GP - "From what I saw on the video, it was only about ..."
Human eyes would detect this much earlier live than the video shows. This is pointed out a few times here, and in the next article.

Parent - "Average reaction time to visual stimulus is about a quarter of a second."
You clearly googled something like "human reaction time", and that is the answer. However, in tests of driving, response time is typically much longer
http://copradar.com/redlight/f...

"It is common practice for accident reconstructionists simply to use a standard reaction time number, such as 1.5 seconds, when analyzing a case."
http://www.visualexpert.com/Re...

That's the average time used by national traffic safety sources. A controlled study in 2000 (IEA2000_ABS51.pdf*) found average driver reaction brake time to be 2.3 seconds. The range of human reaction time is between 0.7 and 3 seconds.

"A few states, including California, have adopted a standard driver reaction time of 2.5 seconds. The United Kingdom's Highway Code and the Association of Chief Police Officers ACPO Code of Practice for Operational Use of Road Policing Enforcement Technology use 3.0 seconds for driver reaction time. The National Safety Council (NSC) recommends 3 seconds minimum spacing (3 second reaction time) between vehicles traveling in the same lane. "

Even assuming you had superior, superhuman reaction speed, you'd travel about 35 feet before you could react.

Driver Reaction Times
0.7 sec -- about as fast as it gets
1.0 sec -- old standard
1.5 sec -- common use
2.0 sec -- common use
2.3 sec -- AVERAGE
2.5 sec -- used in a few states
3.0 sec -- NSC and UK Standard

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This is why driving safety courses tell you to drive with a safe distance and tell you to "drive ahead" ... i.e. look past the car ahead of you (or thru it) to see what's happening down the road so you can react to it.

*
http://copradar.com/redlight/f...

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None of this is to contradict the fact that rare individuals like F1 race car drivers and a few top atheletes and martial artists have faster reaction times. However, that reaction time also includes anticipation and experience. If they are caught in a completely unpredictable situation for which they have no experience then their reaction times drop substantially (tho they are still very fast compared to most humans unless they get confused.

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In this case, the car was going down the road and the pedestrian literally appeared from no where out of the shadows. The police said, from the video data it appeared that the pedestrian was at fault and that it would have been very difficult to avoid hitting the pedestrian.

The converter boxes are worthless even in "near fringe" areas; the signals just aren't strong enough for digital to work. Digital TV requires a minimum of -65 dBm to work barely acceptably, about -60 dBm to work reliably. http://copradar.com/dtv/index.html That's 32 uV and 58 uV into 300 ohms, respectively, which is not a small signal.

OK, I was a little off according to this study - http://citeseerx.ist.psu.edu/v... - 1.1 to 1.2 seconds is the average there, but there are other studies that had higher times, and other sources quote much longer, eg http://copradar.com/redlight/f.... Presumably it takes most people significant time to realise what's happening, not panic, then move your right foot from the accelerator to the brake and the left onto the clutch and press down hard.

Operator error is most likely, especially in the case if the patrol car was moving see Cosine Effect Geometry for information about how this works. The short version is that radar is only 100% accurate when the angle between the target, and the transmitting station is 0 degrees. The further off 0 it is, the worse the error is. Normally this plays out in favor of the motorist, but in certain circumstance the error is added to the actual speed. A little bit if quick trig, and it appears the angle of the radar to the target was between 41 and 42 degrees. Of course, that assumes the GPS speed was in fact correct.

Heterodyne emission detection is how police VG-2 devices () work.