Ok, so I have no idea how I managed to miss this (DAMN YOU PROGRESS RACE!!!1), but there was a video that came along with the Anniversary celebration announcement which hit a few days ago. The actual anniversary is tomorrow, so we're still in time to wish WoW a happy one!
The video is a mash-up of various different cutscenes (both cinematic and in-game) but it ends up being so much more than that, really showcasing the game's history and raids well. If watching this video doesn't give you chills then it might be time to stop playing.
In any case here it is and I'm pretty sure you're going to love it: