If you're familiar with the Saturn (and the PSX hardware as well) hardware, what it can do, and what it cannot, you can easily see that the Saturn Shenmue in that video outbeats anything both systems every produced.
The polygon count is nearly N64+RAM Pack level. Look at those faces. Ears. Lips. And the noses, the NOSES.
The textures' resolution and variety go beyond any level Saturn, PSX and N64 ever displayed. In some shots they seems nearly the same as the Dreamcast version.
I know the game doesn't run on a plain saturn hardware. It's said it was supossed to use the 4MB RAM cart.
But, while the extra RAM could easily offer that rich amount of textures, I'm not sure if it could boost the polygon count that much.
I'm certain it used the legendary VF3 cart, that never got released. It was supossed to have an extra polygon processor chip.