If you have ever ventured into Garadar in Nagrand, you have probably met some of the Mag'har. Serenia and I have been working on our reputation with them for quite a while because we wanted to get Talbuk mounts. If you happen to finish all the Garadar quests and some other various quests in Nagrand, you gain access to a special questline. The questline involves quite a bit of lore and revolves around Thrall's family.
Anyways, at the end of the quest line, Thrall himself visits Nagrand and a rather long cut seen is shown (including a reenactment of a scene from Warcraft III). If you have the time, I would recommend doing the quest line just to see a bit of warcraft lore. Enjoy a couple of screenshots and a little of background info here :)