It's a great video, and does an excellent job of showcasing Azshara's arrogance, and how that trait is almost admirable. The portrayal of N'Zoth is also also very well done, creepy and effective.
I've mentioned before that one thing I enjoy in movies and other media is a good introduction of a villain. This dual introduction of Azshara and N'Zoth is one of the better ones I've seen, revealing both their characters and establishing their power with beautiful efficiency.
One criticism I've seen on the forums is that N'Zoth "outplayed" Azshara, and didn't actually give up anything of value. I think it's best to think of these magical bargains as binding on both parties. If Azshara had made the first bargain, she would have been a literal slave, unable to disobey N'Zoth. Instead she successfully bargained for both power and free will, a triumph indeed.
Ranking the Warbringers video, Jaina's is definitely the best. Azshara's comes in second, and Sylvanas's is last by a wide margin.