The creators of this video, HouseholdGamer, call this series of Skyrim tweaks a "Team Fortress 2" mode. I can see the resemblance, but to me, it looks like like a Killer7 mode.
It looks this weird because there are no textures. None whatsoever. There's just 3D models, the sky and you, which is why everything looks so naked. And surprisingly awesome.
Skyrim Without Textures Looks...Pretty Cool, Actually [GameSetWatch]