I'm not a mechanic or expert. My 2 cents is I think the jackstand placements in the video are wrong. I don't think the pinch welds - they are very thin - are designed to support the weight of the car, that's why people end up with bent (and then rusted) pinch welds.This is probably the best explanation of how to jack up the car, and he is using Kia Soul to demonstrate - But I have zero experience jack up the car this way.
How safe it is for the car ?
Not stated clearly in neither the Kia Soul 2014-19 Owner's Manual - Changing Tires nor the Kia Soul 2014-19 Service Manual - Lift & Support Points but I believe the notches are there to visual show the locations of the four places on the underbody that have been reinforced for the placement of a jack (aka a lifting point designed to handle the weight of the vehicle).
The lifting point is on the underbody right on the other side of the pinch weld between the two notches, not the pinch weld itself.
The kia roadside jack has a slot cutout on the lifting plate for the pinch weld to fit into - Factory scissors jack, Gen 2, 2014-2019.
I don't have a Kia jack.
I assume the slot in the jack lifting plate is deeper than the height of the pinch weld thereby the pinch weld is not subjected to any upward or lifting force.
I assume the wider section of the jack lifting plate is the sole (or main) point of contact where the lifting force from the jack is applied to lift the vehicle.
Thus by positioning the Kia roadside jack between the two notches and so that the pinch weld fits down into the slot, the jack will be properly located to make contact with the small reinforced section of the underbody engineered to be a lift point.