There are a lot of mistakes on this kill, I was not on my computer, so I did'nt have my marks :p I also have world first on Spine 25, i'll try to make another video for this boss when I will have time.
Not hard at all, BWD 25 was by far harder, here it's all about dps. I think you need at least 570ilvl, that's why that was easy for me.
Talents : CTHT (if you don't have nitro boost, try with posthast) / random / Spirit Bond / Toth / Crows (the blink of your pet make the corruption bug) / Barrage.
Spec sv, so remember that multidot also works for us. For pet, hyena or serpent, attack speed is the best buff for hunters.
Just optimize your dps all the time. Regenerative Bloods can be killed in 5sec or can make you loose 20sec, you need to be a little lucky with proc. Barrage will help you a lot with Kalecgos.
Ysera > Nozdormu > Alexstrasza > Kalecgos. Use nitro boots (or posthast) after Alexstrasza.
For Kalecgos, you don't have Alexstrasza anymore to help you killing Blistering tentacles, so make sure you don't pass main tentacle under 75%. Deterrence on second empale. After killing bloods, wait for Cataclysm, and burst (2nd bl up). Do not kill Blistering, this is such a waste of time.
For the last phase, you have to be able to kill Deathwing with only 2 waves of fragments/terrors (you can kill the third wave of fragments, but not 5th and 6th terror). For fragments, multishot/dot all of them, then Barrage. For terrors, focus and kill one of the two, pet usually die at this time, rez, and kill the second.
Berserk won't kill you immediately, you can survive ~10sec.