I've had a Snap-On SSDMR4B0 [1] for at least 25 years now. The usefulness of the ratchet is hard to describe, but easy to recognize after using one for the purpose of driving/removing screws. One big benefit, which only really reveals with longer screws, is the ability to drive or remove much more quickly than a non-ratchet type screwdriver. Also, the benefit is much more recognizable driving screws with significant resistance (i.e. wood screws into hard wood, or concrete screws into concrete or cinder-block). You can keep pressure on the screw, and just rotate the handle back and forth to drive in/remove the screw, reducing the chance of stripping out the screw head by releasing pressure to turn your hand or turn the screwdriver.

If you have ever used a ratchet wrench for nuts or bolts vs. an open-end or box wrench, the difference between the ratchet screwdriver and a regular one is much the same as the difference between using a ratchet wrench vs. an open-end/box wrench to tighten/loosen a nut or bolt.

The ratchet in their screwdriver, from the video, has a ratchet sound very similar to the Snap-On model I have.

[1] Current version: https://shop.snapon.com/product/Standard-Handle/8-3-4%22-Rat...