What do you mean by “works”? It won’t crash the engine or anything but if rotations are different between the rigs then the animation will look bad because rotations are not really retargeted. The video you linked showed rigs with very similar rotations. However if you’ve got something different it won’t look as good. You can try to match the poses by changing the base pose but if you don’t match them completely you’ll end up with different looking animations.
An easy example is a character with a T-pose and another one with an A-pose. Even if they have the exact same bone names and hierarchy if you try to retarget animations from one to the other without changing the base pose you’ll end up with something that looks… not great. I think this is what Neutronux was talking about.