It's just RT shadows so it doesn't have much of a performance impact. It brings more accurate shadows but only the first comparison shows this. The non-RT has the typical very sharp hard shadows everywhere. A lot of people seem to prefer these raster gaming shadows.so, basically Epic+RT setting translate in a more foggy (and a bit blurry sometime) image
funny, some of them look better on Low
and RT bring nothing (i would say "as usual" but personal opinion, not generalisation ) aside FPS drop ...
got the full game with a magazine CD then i bought HW1 remaster, HW:C and HW2 (got DoK free ... but not a huge fan aside for the story, it did not feel like HW ... more like Total Annihilations, tbf )
Most likely low has no TAA which is why you think it looks better in stills but that's still aren't a very good comparison for TAA.