"LEDs flicker at a very high frequency, normally not seen by the human eye, but its intermodulating with the flicker rate on your camera. "
groan... this quote has some truth mixed with nonsense.
LED headlights should do the same thing. (assuming their flash rate is out of shutter phase) What type are the S lights? Looks like the one(s) coming at us is slow flashing. The slower one it's right bulb.
You can the orange turn signal flashing when it's parked (earlier in the cut).
LEDs don't necessarily flicker. They are sometimes pulsed with a variable duty cycle to affect their perceived brightness since the eye acts as an integrator. In the taillight example, when the lights are off the duty cycle would be 0%, when the headlights (or parking lights) are on the taillight duty cycle might be 50% (perceived as half brightness) , and when the brake pedal is depressed the duty cycle would be 100%.
That pulse rate doesn't have to be very high. Movies are at 24 fps, standard TV 30 fps. I'd guess standard LED taillights are using somewhere around 60 Hz since you
can actually see them flicker with the naked eye if you look quickly from one side to the other. Certainly less than 100 Hz and not what I'd call "a very high frequency" (e.g. VHF is defined as above 30 MHz).
The orange light at 0:23 in the video is flashing because the turn signal is on.
Since the frequency of the LEDs' strobing and the frame rate of the camera are different, phase isn't so much the issue. You can look at is as the relative phase constantly changing, which gives rise to the flickering you see on the video. It's beating. I linked to this before:
Beat (acoustics) - Wikipedia, the free encyclopedia. Even though that's in the context of sound, it's the same phenomenon and the same math. In fact if we assume the camera is at 30 fps, we can calculate the LED strobe rate by measuring the beat frequency.
Hopefully that's a thorough and clear enough explanation.
