Holy Crap! Some very important stuff got shown in this trailer!
@1:02 - There are a bunch of giant Humanity looking creatures in the pit. They can be either friendly or hostile but this could be a very big slice of lore on the 4th Lord Soul (The Dark Soul). The Humanity item description says that the item is only called Humanity, so it isn't actually humanity. Some rumors on the DS message boards say that the Humanity item is an extension or creation of the Dark Soul.
@1:06 - It might just be some deformed Titanite Demon but the area (reminds me of the Abyss but you can see the floor) and the cut-scene intro of the monster might suggest that it's pretty important. It may be one of the beasts that lurk in the abyss and perhaps the reason that you are in Oolacile in the first place.
@1:13 - Bam! It's Lord's Blade Ciarran. Might just be a common flashy enemy but I'll call it right now, it's her. Though the camera angle looks like you are Ciarran or just wearing her gear. So she may not actually appear in the game so we can interact with her but atleast we'll get to know what she looked like.
@1:20 - And finally this.... this probably the most hard to explain clip. It looks like a Black Phantom Dark Knight (or maybe an online PvP invader wearing the Dark Knight armor set) is stabbing you in the face while you are in the coffin which leads to the Gravelord Covenant. This raises too many questions...
There is also the final clip with the giant in armor who is sculpting something on a rock who says "Thou will understand one day" but I'm pretty sure he's just some NPC who has minimal relevance....... or it could be just a troll comment to all Dark Soul players from Miyazaki about the effing Pendant debacle. Freaking prick.... -__-