The issue here is go a google search and you will find 10 different lists and rankings that are so all over the place that you'd think the top 10 or so countries in the world would be all about the same. They all would have different education systems. It would also depend on whether a country is community focused or individualistic focused. Some countries teach children to work together to solve problems some teach them to do it themselves and not work in groups. I lived in both systems growing up.
I honestly think it comes down to an individual and how they prefer to learn. Forcing certain kids to form into a certain routine will not work for them and they just give up as the pace may be too quick for them. Me personally i liked to get shit over and done with that way I have more free time. So for example a school project that was meant to take months to do i would work hard for two weeks (5-7 hours a night after school) to get it done. Then i would kick back and enjoy my time off lol.
My only flaw that i still hate to this day is that at a younger age school for me was too easy, it actual made me disinterested in learning later on in higher education and i was going through the motions of study and over study without absorbing anything. Took me a while to get out of that routine.
Generally speaking when i got older i go stuck into the trap of i must study a lot to get good grades to get into uni. The issue there was i started over thinking it during tests and would question if i did something right or wrong and would fail as I over studied but in practice I wasn't absorbing information when I studied. When i took the relaxed approach I went with my gut intuition of what i knew and stuck with it. Uni for me was similar, when i studied longer i then started to second guess myself (ie. in Maths when the answer was 0, i wondered did i do it right, did i have the calculator on degree or should it be on radians).
My routine switched to a more relaxed, rock up to class and not take notes. Just sit there and listen and absorb the information. Then at the end of the month i would borrow someones notes and copy them. What i found was when i put 100% effort into concentrating and not dividing my attention in listening and writing I retained information easier and when i wrote it out later i still remembered like it was a fresh lecture in my head.
Now on the flip side I know people that cannot be that relaxed and need to write out a maths problem 10 times before they understand it.
So concluding. It is hard to judge from that video as it is very short. I think a balance between structure and freedom needs to exist, otherwise some kids will just go completely offtrack. 3 to 4 hours a day at school seems a little short, however the life experiences these kids learnt i learn after school because i've always had insomnia and was always keen to learn things late at night, so i can't judge for everyone. If you can give a child confidence in people skills, logical problem solving, and not giving up and be determined to get there, they will be able to handle most adult jobs later on. I also think kids with greater intelligence need to be guided more to ensure they do not become disinterested, make them challenge the way they think and solve problems.