Looking at that video, kinda looks like what I'd expect a port of GTAV to look like on the ps4. (again kinda)
But something just seems off with the lighting, too bright, like maybe missing shadows or something. Like they've left a setting turned off or something that adds shadows.
Anyways, the reason people have so much of an issue with this game's graphics being like this is because it looked significantly better when shown off 2 years ago. If they hadn't shown that off, and had revealed the game the way it looks now,many of the comments would be "yup, looks like a cross-gen game" rather than "looks like a ps3/360 game"
Edit: But also, I noticed that their previous gameplay vids had some framerate hiccups when performing some actions, the game looks silky smooth in the video now.