I don't know if it's the same guy, but I watched videos of a guy laying aerated concrete blocks himself and it's much more work: you need a good supplier of blocks with good dimenions, you still have to rasp down and sand down the tops of each row so they form a perfectly horizontal plane for the next row or the glue won't catch, door and window gaps are tricky and upper floors are even trickier if you want to use aerated concrete for the floor/ceiling.
Expertise required is getting the corners up precisely and being able to use a laser level and a string. You don't make ceilings/floors from these, the best option for multi-story house would be to have the floors done from a pre-fabricated concrete blocks which a crane would put on your walls https://baltparma.lt/39-large_default/perdangos-plokstes-pk...., this will give very stable floor. On the other hand, in US there's lots of framing expertise as you're saying and the options I've laid out are probably not as accessible.
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