I really enjoyed the video.
Rarely have I seen it recommended to "build" the abdominals with the same muscle building principals as other muscles.
There is an over compensating trend to focus on fat loss, and avoiding cardio to prevent muscle loss.
I remember from long ago, it was advised never build up your obliques because that will lead to making your 'love handles' stand out.
I think way back in the 70's and 80's they thought of healthy fat as around 20% for men and less than 10% just unobtainable or unhealthy. Probably all that Eisenhower high-carb diets to fight heart disease philosophy. If your Triglycerides are constantly being pumped sky-high on carbs and grains.. I think getting low body fat would be.. challenging.
Looking at a lot of guys with decent abdominals showing, it seems its definitely possible to get defined rectus adominals that look like train tracks.. but then the sides look rather emaciated.. or malnourished.
The obliques seem to form a healthy looking "frame", which does firm out the waist line.. but we have to keep in mind what the goal is here.. to look (as well as be) healthy.
Fat in the love handle area can act like cheating "spackling paste" and fill in that area.. but its not healthy.
I'm self critquing here.. because I think I'm guilty of ignoring the obliques and focusing too much on fat loss.
Its a given a little more fat than is essential for life is "required" to make the hormones (like testosterone or growth hormone) that enable muscle building. But which fats those are (omega 3-6-9?) and how much over "essential" is needed instead of what merely leads to excess calories to store.. is difficult to figure out.
Dogma and broscience seem to just say "splurge" and get fat to grown, worry about cutting down later.
That sounds less than optimal.. even if it is different for each person (but even that doesn't sound right.. I think its about the same for each man).