1 Lambert: Obviously this Dwalin knows about the secret dwarven passage, otherwise why else would he be here?
1 Mordekai: Metagaming. I like it.
2 Draak: Draak think so too. But how we get dwarf to tell?
3 Kyros: I have some subtle psychological magic that can help to gently persuade people to our point of view.
4 Lambert: You do?
4 Kyros: He tells us where it is or I fireball him.

Metagaming is using out-of-character knowledge in a role-playing game scenario in which ideally the player should remain in character.

I didn't expect there to be a Wikipedia article on this concept, but indeed there is.

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2015-10-19 Rerun commentary: There is also a possible in-character justification for Lambert's opening statement. If you assume that there is such a thing as Fate, Destiny, or Higher Purpose, or one or more Gods controlling events such that things happen For A Reason, then you can justify speculating along the lines of "if X happens, then there must be a reason for X which relates to my current goals".

So rather than Mordekai's line about metagaming, this could work just as well if the opening lines had gone like this:

1 Lambert: Obviously this Dwalin knows about the secret dwarven passage, otherwise why else would he be here?
1 Mordekai: Yes, the will of the gods is not to be denied.

Transfer this to the real world and...

Yeah. People who invoke destiny or fate or the will of gods in an attempt to explain events are actually metagaming reality.