In an ideal game-world a DK MT for Sarth would not need to spec for the fight or heavy assistance from the support. But things are rarely ideal. And let's not forget that Dilbrt is just starting to tank the encounter.
Every single DK tank with the title that I've spoken with (and it seems all the ones our tank class lead has) described the timing of cooldowns in conjunction with the healer abilities to be key when starting out. There are other things like timing the portal kills and dealing with the drakes' DPS budget, but this thread isn't about general Sarth 3D strategies, it's about MTing the encounter.
Once you guys get into the groove then, like all encounters, you'll figure out which tricks you need and don't, when you need them, etc... I assume from what I know of Dilbrt on these forums that he'll be able to figure that out.
Just wanted to clarify my two cents above.