There's one basic thing you need to know about CMYK, and that is, you need to add more colors over black to get a true, deep black. When printing, if you don't overpaint the blacks they will look washed out, grey, and cheap. That's what you need to know--unfortunately, it is not mentioned in the video.

Unfortunately it's not that simple. It's almost a science how to combine CMY and K for consistent printing. But nowadays people in general want to get on an expert level by watching a 4 mn YT tutorial or joining a facebook group.

For best results, printing on an offset press also requires that an appropriate ICC profile be assigned that's device-specific. Regarding flat blacks, I ordinarily create a black profile in InDesign that is 70/70/0/100 which usually gives me a robust, full-coverage black on offset presses. Of course, today's digital presses such as the HP Indigo have more color latitude than standard offset presses and are capable of achieving enhanced color by using using additional inks (e.g., CMYKOVG).

DrDave, I originally received that 70/70/0/100 recommendation directly from the offset printing company I've frequently used. I suspect the absence of yellow has more to do with registration than saturation on offset presses.