Field, stripping ...
The 1-handed grasp technique does work well for a number of folks to manipulate the slide backward on the frame and hold it in the right position to remove the slide stop lever. Aligning the rear point of the slide stop notch in the slide with the rear point of the rounded frame notch (for the slide stop lever) works well to position the frame and slide for slide stop lever removal.
Reassembly works the same way, although a tip not often seen involves moving the barrel rearward a little so the bottom barrel lug isn't in the way when the slide stop lever's pin is pushed into the frame hole. This can be done by either tipping the pistol so the muzzle is angled up (and gravity pulls the barrel rearward out of the way of the lever's pin), or, holding the pistol horizontal and pushing the barrel slightly rearward by gently pushing on the tip of the muzzle (and then holding the pistol in the horizontal position until the pin has cleared the front barrel lug surface). Otherwise, trying to shove the tip of the steel lever's pin against the side of the barrel's steel lug surface can become tiring ...
Depressing the ejector, firing pin safety lever and sear release levers can be easily done by laying the shaft (side) of a pin punch gently against the top of each lever in turn (longer first, working backward) and lowering each lever flat, even with the top of the frame, as the slide is pushed over them and onto the rear of the frame. (Sometimes a bit of difficulty can be experienced when pushing the sear release lever downward, due to sear nose/sear release lever foot engagement conditions, but that's another subject for which a couple of easy answers are available.)
I didn't have time to watch the entirety of both videos, but I definitely wouldn't remove the side plate by pushing on the end of the side plate's pin.
It can put unintended stress on the side plate where the pin is staked to the side plate body on the outside of the assembly.
The pin is basically pressed & staked onto the flat part of the side plate body. If the pin becomes loose and is able to be easily turned (rotated) within the side plate body using finger tip pressure, armorers are taught that it's time to replace the side plate (before the pin breaks free of the plate itself).
Breaking the side plate's lower legs free from around the recessed left end of the sear pin is usually done first, before the side plate is removed from the frame. While it can be done with a pin punch, a simple technique using a plastic mallet to snap the pin out from between the legs without damaging anything has been taught in the last couple of armorer classes I've attended (although it's important to do it carefully so the legs don't become tweaked, bent or broken - requiring replacement of the side plate). There's a similar way to snap the legs around the recessed head of the sear pin which reduces the risk of applying uneven force to the legs and tweaking one or the other of them, too.
Complete disassembly of the frame isn't something recommended by the factory unless the person doing so has the knowledge, training and some experience.
It's not that it's particularly difficult, but not understanding why things work the way they do, and lacking some understanding of why things are best done in a certain order, using the right techniques and simple tools, can understandably lend itself to risking damaging parts or adversely affecting the normal, safe operation of the gun.