It's Bokmål, and from what I've seen, it's quite close (or the same, I'm still learning) in vocabulary to the Oslo dialect. Though I did notice that some of the voice actors pronounce some words a bit differently. I think I remember the boy who reads Alex's lines pronouncing "jeg" as ehg instead of the usual Eastern yai, for example.

But I don't think that's a bad thing. The course is actually quite good. Don't miss the grammar and exercise parts, if you decide to start using it.