I watched your 1st video. I think you meant to say "air to air heat pump", not "inverter". They're very good at heating the ceiling while leaving the space we inhabit cool. Try using a IR temperature gun (eg.
https://www.amazon.com/dp/B00837ZGRY ) to find hot spots and cool spots in the rooms. If there is a large temperature difference, use a circulator fan (eg.
https://www.amazon.com/dp/B004XZDCQW ) to move the cool air up and force warm air down. I like to use the larger ones on the slowest settings for quiet 24/7 operation.
It seems counter-intuitive, but it makes a huge difference both in comfort and energy savings. I've now lowered my thermostats down to 18C, and it's just perfect!