Singing this Note is IMPOSSIBLE!

Hello, I'm coming to your video pretty late but anyway, my response will be super-duper-long (I can't resist).
I'm a piano player, a music composer, an occasional flute player, a tuning theorist, but (and this is important here) I've done a lot of research in digital signal processing.

- - So, first of all, if we examine the musical instruments where the pitched waveform can indeed be periodic (like flutes, bowed strings, the voice and so on), we find that the frequencies of the component sinusoids (ignoring the noise) are integer multiples of the fundamental frequency. But the super-important thing here is that this is not just a matter of our physical reality or of the phenomena valid on the planet Earth, these things hold even in the abstract world, independent of the related physics. By which I mean, if you take any possible periodic mathematical function imaginable and you want to express it as a sum of sinusoids, there's no way you could ever find a non-integer multiple frequency in your periodic shape. What does it mean for someone who's making electronic music? That if you take any possible sound recording, cut a 5-millisecond segment out of it and play that 5-ms segment in a loop forever, the sole act of looping limits the frequency content of your sound to integer multiples of 200 Hz, even if the original sound contained whatever other stuff there was in it (several people didn't believe me when I told them).

- - Now imagine a sinusoid whose frequency would sweep continuously from 20 Hz all the way up to 20 kHz and imagine summing this sinusoid with itself delayed by 5 ms. What will you get? The multiples of 200 Hz end up having double their amplitude while those that are exactly in-between disappear completely (watch the phase cancellation there).

- - But now let's go back to our original loop containing multiples of 200 Hz and sum it with itself delayed by 5 ms and given in opposite polarity. So, because the loop takes 5 ms, then delaying it by 5 ms does nothing much to the sum. But reversing the sign means that we're in fact subtracting, not adding.
Voilà, suddenly the whole sound is gone! There's nothing left at all.
But hang on, I said our loop could never include any frequency that's not a multiple of 200 Hz, right? So let's again take a sine wave whose frequency would sweep from 20 Hz to 20 kHz and run this through our inverted delay effect. What will we get? The frequencies that are integer multiples of 200 Hz will disappear completely while those that are exactly in-between (100, 300, 500 etc.) will get their amplitude doubled (have you ever heard what it sounds like?). And if several subsequent 5-ms delays follow and their signs keep alternating, the basic idea is the same (the multiples of 200 Hz almost disappear instead of really disappearing).
So now when I try to force a multiple of 200 Hz to appear in my modified sound, it just can't. And if this thing holds in the purely mathematical abstract world, it necessarily has to be true in our real world as well.

- - So if you have a tube that's tuned to a fundamental frequency of 200 Hz when open at both ends, it resonates at frequencies that are multiples of 200 Hz. Now try covering the edges of the tube with your mouth but leave the inside of the tube almost untouched. Because the other end is still almost open, the resonant frequencies are still close to integer multiples of 200 Hz. Now try to get your lips closer and closer together, but stop just before they would actually touch each other as you don't in fact want to close your mouth. Now the smaller the hole at the other end of the tube is, the lower the resonant frequencies are. If the other end were entirely closed and if the end effect phenomenon did not exist, 200 Hz would fall down to 100, 400 would change to 300, 600 would change to 500 and so on (right, the waveforms keep changing their direction, that's those alternating signs there). So in reality they're not exact odd multiples of 100 Hz but sufficiently close to them.

- - Now imagine taking a tiny loudspeaker that woud cover the opposite end of the tube entirely and imagine playing the sine sweep through that loudspeaker. What would come out at the other end of the tube? The odd multiples of 100 would get maximum amplitude while the even multiples (which are all the multiples of 200) would be swallowed by all the phase cancellation caused by the specific delay.

- - So, that's just about it. I encourage you to run a sound editor on your computer and try some of those things on your own.