4 Horsemen
How did you handle switching the tanks on the caster side? I see them running around the same time. You just turn them around and set auto run, the do the same on the second and then go back to the first to stop him?

And on the melee side. Did you have a healer on the second tank or does he keep himself alive untill the first one is burned down. I also noticed that you popped heroism at the second boss. Seems kind of a waste since you kill the boss in less then 30seconds. Could have done it earlyer. Guess you don`t do it at the start of the fight because of the debuffs once you get to the second one?
That's it exactly it, auto-run and switching between windows to stop and start. I start the run every second or third void zone depending on how busy I am with the front side. Most of my attention goes to the back end, though.

I do lose a bit of time on the heroism, but often there's some distraction on the back side such that I don't get to pull Rivendare immediately after Thane. I usually have the most trouble with burning Rivendare down before the marks reach an unmanageable level and so I want heroism for as much of that engagement as possible.

Seems like a pretty straight forward tank and spank fight for boxers with a LOT of healing.
And a lot of frost resistance. Getting my characters spaced is still important, as is using prayer of mending. When I made my first attempts at Sapphiron, I tried having my team eat all blizzards, but even with full frost resistance suits, they still die very quickly.
What is the exact group setup of your raid? I seen some shamans, 2 paladins, 1 boomkin and atleast 1 priest and mage.

Also wondering about your tank macro on the paladin. Mind sharing it?I know I ask a lot
In the movies, I use 2 paladins, 1 druid, 2 priests, 1 mage and 4 shaman in the movies, all of them with 10 man and heroic gear only. When I first started and completed Naxx ( save Kel'Thuzad ) I was using the same group, but replace 1 priest with a druid and 1 paladin with a death knight. I'm much happier with the new arrangement.

As for the macro, it's embarassingly simple. I don't mind sharing it, but it's not impressive at all:

/castsequence reset=8 Shield of Righteousness, Hammer of the Righteous, Consecration, Holy Shield, Judgement of Wisdom

Consecration isn't glyphed and judgement is talented. As a whole I get about 3.5k - 4k tps.