I don't find it as strange as he does that the i5-8400 has such a low base clock speed, considering its lower TDP target. It'll be interesting to see what does actually happen when pairing these CPUs with the non-Z chipsets, i.e. whether they will still mostly run at 3.8 GHz all cores or not.
That's a good point, these were tested in high end Z motherboards, when the more budget boards are out, then the cpu might not get up to speeds they did on the Z boards.