Well, for starters, that guy's using water sprite, not wisteria...
An idea that I've played around with in my head was to use Duckweed, Water lettuce, or some other floating plant that is well known to grow fast. You want it to be growing emergent rather than submerged (like he's doing there). You could probably remove more nitrate than with just a floating stem plant, although with duckweed (which probably your best bet for raw nitrate sucking power) you'll need to find a way to prevent it from leaving the tank (like a sock on return). As far as light goes.... I don't think it matters. The more light you have, the more plants can utilize nitrogen. By using floating plants, you're largely circumventing the need for CO2, so you could get away with a lot more light than in a normal aquarium.
My concern with this is how it would impact the display tank if done correctly. Too much nitrogen sequestration could cause low nitrates in the display tank, especially in anything beyond low light, leading to trouble. Certainly an interesting prospect though if you are especially averse to nitrates for whatever reason.
