Now unbalance the load and see what happens. Unscrew 3 of the 4 bulbs on one branch only, leaving all four bulbs on the other branch screwed in.

The real problems were left out from the video. This shows only an open neutral if it broke while turned on already, and the load is well balanced. Those LEDs are fairly equalized in load, so the voltage will not fluctuate. BUT. Once you try to start them like this, their on-time will vary and there WILL BE a voltage imbalance between the 2 sides, which will lead one side to stay dark, while the other side will get way too voltage and blow out (and i suspect, one by one, but quite quickly) And this does not only apply to LEDs, incandescent bulbs vary in resistance as well. You can do this experiment on 12V by using 2 incandescent car bulbs in series and try to run them from 12V. at around 80% of the times only one of the 2 bulbs will glow. (Kind of random) - This is a way safer experiment than using 220V, in my opinion ... If you run them from 24V, one side will surely blow almost instantly, so run them from 12V , 2 bulbs in series. Had once a car which some "smart" mechanic wired 2 relays in series to control the headlights. It worked when you switched it on first, but once you tried to use the flash, and cut off the electricity for a split second, it went dark. Took me about a half an hour to figure it out, as i did not expected such stupidity.

Thank you

Hmmm Okay, So are you saying that each set of four are wired as normal (in parallel) and the two sets are then in series? Yes its interesting but a tiny bit more clarity would be helpful. And although these bulbs are LEDs they are still simple devices. I once was having work done on my house and the worker snagged and broke the neutral Service Entrance Conductor, That fried every electronic appliance in my house...expensive mistake for sure.

Wondering where ya got the 3 phase 208V WYE source... it is going to be 220V as there no 3 phase power judging by the distro panel you showed, ie 220v center tap neutral single phase or did I miss something? It could be but ya seem to be showing more residential stuff not industrial.

"An open neutral"

Or .... you might purchase a ( one off , UK / Europe , 230 Volt bulb ) and connect it between BLACK and RED .... which would work OK , without the WHITE neutral needed ( a trans Atlantic business deal here ? ) Ha - Ha .. DAVE™🛑

That was exceptionally confusing. Might want to tailor your content to fit a slightly wider/dumber audience (pls).

Jittery, too fast, non-stop commentary, not properly zooming onto the component to show what exactly you talking about. 30 seconds and I was out.

American electricians have a lot to learn from western European practices.