The lights in question are RGB, possibly even RGBW LEDs, that mix their colours by using pulse wave modulation – which means a chopped up waveform based on the 50Hz main frequency. If they are cycling through the colours, as they’re doing here, as red goes up, blue might be going down. They don’t dim, they simply change the amount of time they are on full – so they flicker by design. You can see a flicker on 25 or 50Hz video, but it will be worse on 30/60Hz as the difference makes a big impact – worse than fluorescent or discharge lighting, which at least do ramp up and down in brightness very quickly, rather than snap on and off quickly.
