How in Hermaeus Mora's name does Arngeir know the names of the people that become Jarls after the negotiations.
I didn't see a note on the table with the names, I didn't hear anyone say the names.
They don't go out except for when they want to "worship" kynareth ([censored] traitors).

Seems they know "a friend" like we do who knows I just shouted Fus Ro Da in Bleak Falls Barrow and caused quite a disturbance.

Uh...Um..Eh....IT'S A SHOUT!

The "Know about things we shouldn't" Shout!

The guards know this shout too.

Ulfric DID study with them at one point...

...And they DO have Paarthunax as their leader. Maybe one or the other informed them of this?

their names are visable at your pointer if you point it at them, that's how he did it ye