Do the different trainers have differing hysteresis/lag in how they respond to slight variations in input power/cadence? In the video you linked to earlier (I’ve seen it before BTW) it seems like his trainer responds within a second or two which is what I was expecting whereas my (well my wife’s) H3 is more like ten seconds and then seems like it overshoots. This may be a setting on the trainer itself, dunno at the moment.
In the first video at around the 6:40 mark he varies his cadence quite markedly (between 80 & 120rpm) but there’s little to no change in the displayed rider power (<5W). That’s what I was expecting but it would appear that what’s being displayed is smoothed.