My issue with most of the World of Warcraft soundtracks posted on youtube is that they all lack the ambient sounds, which for me were just as important.
I already noted how I actually had to download a WotLK client to recover the night time ambient music of the original Azshara sigh.
I did manage to dig up an alternative of sorts though:
there's this chap on youtube who created a Warcraft Atlas, i.e. he traveled through each zone prior to the Cataclysm and recorded all landmarks and the sort; because he actually rides through every area, you can listen to most ambient sounds as well, though, of course, you will get either daytime or nighttime ambient sounds in most cases, not both.
That aside, do you gang remember the 2005 Rite of Passage? The absolute best take on Blackwing Lair.
Sadly, I can't find it in good quality, but here you go, it is still extremely good.
Blackwing Lair: Rite of Passage (Part 1)
Blackwing Lair: Rite of Passage (Part 2) (note the Forsaken mage at 0:30, it will so make you want to play one; also, that Thunderfury's trailing defiantly through the air right before Nefarian lands at 5:40 - would so want to main tank Nefarian, pity my very packed schedule is so unlikely to allow me to raid).
cos barrens so big;you have to fly by 
