Good point Mr D..... most new cars and bikes have some LED lights, whether DRLs , stoplights ........ and these usually appear to be flashing/strobing when videoed - quite normal to the eye, though. Presumably it's something to do with the LED "driver" used.
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Doesn't excuse the cyclists with their uncontrolled, retina-searing strobes, though! You might see them, but then fail to notice the tree, pedestrian, unlit skip or whatever that's also in front of you, as the glare slowly clears.