If you must put it in a nutshell:
Nords- Nords (Scandinavian not the Elder Scrolls race) with heavy Egyptian and Celtic influences (mummifying and "stonehenges" respectively).
Redguard- Mostly Middle Eastern with alot of the Moors thrown in.
Cyrodiils- Mostly Roman/Italian. Have some Native American/Japanese/(maybe?) African in Niben
Bretons- Celtic Britons in the Reach. French everywhere else.
Altmer- Japanese/Chinese sort of. Indian maybe with social structure and maybe architecture.
Khajiit- Persian. With crack. Lots of crack.
Dunmer- uh...dunmeri? Dunmer culture is very alien/original. Native American/ other nomadic tribes with the Ashlanders. Architecture is Mongolian/Mesopotamian in style.
Bosmer- bones in trees
Orcs- Shamanistic/Animistic cultures from around the world.
Argonians- wierd trees that weaponized math
The non-human races are hard to pin down.
By "dig yourself into a rabbit hole", I think he means that once you start to say that X TES culture = Y real world culture, that immediately becomes a contestable point, as all the peoples of Tamriel draw on multiple sources of real and fictional cultures, and declaring that one race mirrors another is missing the point of really amazing world-building. Not only could some of these perceived similarities be incorrect, but there could be varying degrees of similarity. There could be direct comparisons, there could be minor ones, mistaken ones (meaning they're actually inspired by something else), or that multiple TES races are influenced by the same societies. More likely than not, those real histories you think are anologous to TES ones are themselves inspired and influenced by their precursors and contemporaries. The point is, the inhabitants of Nirn are a patchwork of many different pieces from our own history and mythology as well as original creations.
This is my feelings too. The cultures are so well built, trying to give them direct real world parallels really don't work too well.