Ray tracing is basically realistically simulated lighting. Simply put, as a dev, you only need to set a light source, it's parameters and the rest (light distribution, diffusion, reflections, refraction) is handled automatically by the tech.
As a user, it's a bit comparable to the "pixel shader" leap of the early 2000's I think. Not as extreme - when that tech became used on games you had to literally buy a card that supported it or the game couldn't be run - but it's still in it's infancy.
Whithout it - as it was the case in Metro Exodus, for example - all of those need to be "written" in. That's why you get unnaturally lit or unlit areas, because it's independant of an actual source, or focal point. The video just points out how "well" the lighting was made whithout the added benefit of automatic simulation. At least in the open areas where the detail is a bit harder to notice thanks to the nature of it, "illumination".
The visual fidelity between the first two pics is telling. The first seems like your run off the mill lifeless empty area part of a grander open world that simply didn't need developer attention while the latter seems part of a well crafted ambient environment.
Some extreme cases of Ray Tracing benefit probably wouldn't be possible using the standard approach, but to be able to see them, they must be made so as to take advantage of the tech (one example of this would be the Minecraft cristal cubes).
There simply hasn't been a game made to fully display what Ray Tracing is capable of. That said, such a game would probably require much more processing power than current gen Ray Tracing cards can handle. So we need to make due with crumbs, very pretty crumbs, but probably not much else, for now.
All of this isn't to say you shouldn't buy an RTX card. The 2080 is simply a damn good card, RTX or not, and the price is the same as it was when the 1080 launched (around 750 euros), at least in my area.