If you pay attention, you can see Artorias himself at the end of the trailer.
As for the DLC, it is sorta disappointing that they're doing it, and charging so much for it. It's one of those things, though, where I'm pretty damn sure they weren't planning it, but when they got funded for the PC version they decided to add in all the stuff that wasn't ready for the main release.
So I'm happy to see a PC release (especially since it's pretty much been confirmed for Steam) and I'm happy that Bamco and From take feedback like they should (rather than insult the consumers like some other companies do), but I don't want to pay 15 bucks for this.
If it comes to Steam, I'll just buy it on there. Maybe.
Although, that swanky new kick move that's shown off in the trailer may be worth the purchase. Hmmm...