It seems to me that this game doesn't actually take in account all the seemingly existing light sources when computing the shadows: see for instance at around 7

It seems to me that this game doesn't actually take in account all the seemingly existing light sources when computing the shadows: see for instance at around 7:45, there is an obvious light source in the bottom right region (actually a bunch of synchronized pulsating lights on some sort of cylinders) which clearly should affect the surfaces close to it, but it doesn't in either mode! In the next comparison, there's a fire burning close to a wall, and likewise the fire doesn't seem to emit any light on the wall. Actually, the commentators do mention that there isn't that much dynamic lights handled in the game, limiting the effect of RTX. I don't know how that RTX tech is working, but from what I've seen of the port of Quake2, it looked much more convincing - did you see it before making that judgement?