SAKs are quite strong, and so long as you don't take on something stupid big then you may well get away with it. Needs must. Do it regularly and you will break them.
Tying to a stick or weight will get more chopping power but also a quick way to break the knife. The knives on the vid aren't up to sustained use that way. Thick stock and the right heat treat that leans to tough might, but the examples shown don't.
Wedges do work but they take time. Bushcraft is living with the basics which means some tools to get the job done. Survival is get home to civilisation in one piece with what you have. Speed or deliberate, as both are a choice???
A SAK is replaceable. A high cost custom should be able to what it was made for. Its your call. Ever job has some risk, every blade some luck built in. Do something risky and the luck might run out.
Practice and gaining the experience requires finding the limitations so some risk is involved. Best done before it matters.