So I'm just playing through the part from the demo where you have to , and I notice his voice is not the cool rasping one from the vid. It just sounds plain now, like the dark elf voice from Oblivion

Anyone that has gotten further in the game can tell me how the Dunmer voices are? Would be a shame if they just sound like any other race.

They sound like Warcraft Blood Elves

The guy you mentioned in the OP is the only one I've seen so far that really sounds like the one (singular voice actor) from Oblivion

Not every Dunmer is voiced by the same person. There is a ton of voices...or I just svck at remembering what they sound like later.

So far, all the Dunmer I've met have this deep, aristocratic, but clearly threatening accent that ranges from British to Middle Eastern. It's not what I expected, but I like it.

The Dunmer voices are among the few I actually like in this game; most of the voice acting and/or casting is absolutely atrocious.

Was it me or did he sound like he had a Cockney accent?

He does "kind of" but there are a few weird-sounding pronunciations in there...

Edit: typo.

He sounded Australian to me.

But it all makes sense. This is 200 years ahead of Oblivion and these people may have lived in Skyrim all their lives, so they wouldn't have the same accent or voice.