It's not the case that I know how to implement better water, it's that Bethesda themselves know how to do better water, and they did it nine years ago.
I don't think you can make that determination based on a a few seconds of footage from a trailer, that's showing a game that's more than half a year away from completion.
I am positive I read somewhere that the water works with physics, and that if you stand in it, it will flow around your legs, and it will automatically form waterfalls (I'll be damned if I could remember where, though; it's not in the GI mag). And I really have a hard time thinking they made a bunch of unique static meshes to look like streams and waterfalls, that form-fit perfectly against the world geometry and wind all around the province. I really do believe the water (streams, rivers, waterfalls, rapids, etc) is formed dynamically.
But even if it is completely prefab static meshes, they're more versatile than anything I saw in Oblivion. In Ob, you had flowing water coming out of rocks, going only in one direction, that couldn't be more than knee deep (before being able to ruin the effect by looking under the surface to see it's not water at all), and you could only change the elevation of "standing water" when crossing cells. The flowing water and waterfall meshes that Oblivion had, all looked identical. I don't think I've seen two identical waterfalls or streams in Skyrim's shots, yet.