Here are some more videos. I think the roundtable discussion on the game is also among these videos (don't forget to click "next page").
The "Twilight" is a world, or dimension, separate from Hyrule. Sort of like the Dark World in LTTP maybe. All I know is that it's intgral to the story, and when Link first passes over into the Twilight, he gets turned into a wolf, but gets rescued by a mysterios girl with odd powers.
Here's what I know (some spoilers maybe, I dunno): Link starts out as a ranch hand, in a remote village outside Hyrule. He wears ordinary clothes customary to taht village. His adventure begins when he's asked to attend some meeting on the behalf of the village leader, and appereantly there's a girl he likes - in one video from E3, he showed one of his most emotionally convincing faces when talking to her I've seen in a Zelda game, even if it was brief - I hope he continues to show more emotion than in previous games, and this time there appears to be a girl that Link openly likes.
Zelda's in the game, and one official concept art shows her holding a sword. Ganondorf hasn't been mentioned yet, but he may be part of the plot. The world is so vast that Link almost has to use his horse (which you can name yourself) to cross it, Anouma says. Hyrule field itself is
humongous. One of the E3 demos, the horseback fight with a boss and his boar-riding minions armed with fire arrows, took palce in Hyrule field. Link can now use horseback swordplay, and Epona seems to be more easily controlled than before.
The game is "darker" than before, but not to excaggeration. This is Zelda we're talking about after all. No blood or anything. One of the E3 demos showed Link's girl interest being shot with an arrow in the back, and taken away along with a smaller boy. The boy appeared again later, unconscious and tied to the top of the spear of the boss in command of the boar-riding minions that fought Link on Hyrule field.
I sincerely hope that this game won't feel like a repetition of Ocarina of Time - that the dungeons will have the same old puzzles, that the bosses will be the same old thing, that the plot will incorporate Zelda being kidnapped. I want her to put up a fight like she did in Wind Waker! I have faith in being proven wrong, though; the way to fight the boss of the Forest Temple was quite cool. Anouma says that they want to surpass Ocarina of Time - if they succeed in beating my most favourite game ever, I'll be in videogame heaven.

They say that they are working heavily on perfecting the game, smoothing out the stiff-looking animations and stuff. So this game is indeed looking very, very promising.