Well...it isn't that good, but don't let that keep you down. You need to spend some more time on your cinematics, make them last at least a few minutes.
Ok, so, the terrain was pretty awful, the doodads around the acolyte seemed to be randomly placed, behind the demons there was complete emptiness.
The story didn't make much sense either because I doubt the burning legion would ask a simple acolyte to join them more then once. It's a simple acolyte, not Kel'Thuzad.
The screenplay was ok, I guess. I didn't really notice any major spelling errors(but I didn't look too hard). You misspelled when as wen.
My advice is to take a look at some other, more popular cinematics and get some inspiration from them. You can check out my Sect of the Holy Mother series(located in my signature) where you can see a huge improvement from part 1 to part 8, plus I'm sure you'll love the story.