I'll add a couple things. In response to sonder as to why they have the hunter, it is probably for Probably Ferocious Inspiration(3% damage increase to party). I don't see the Marks buff, and I couldn't pick out an explosive shot, so it was probably Beast Mastery. So that could be why.
The zerg method is WAY easier if you have the DPS. The regular way still takes quite a bit of dps and then you have to add on about 4 times the coorperation to pull it off.
I got bored one afternoon and decided to make a pug for this on my rogue. I stacked complimentary melee classes with an enhancement shaman for Blood Lust. The DPS average came out to about 5k so about 42k dps total if I include the tank. We could have gotten away with a bit less but not much. I think the required numbers are 36k+ for dps. If the dps is way too low, you'll get the 2nd drake. If you're dps is high, but not quite enough, you won't have enough time from 35% and when Tenebron decides the person that is kiting him is going to eat the ground. This is one of those fights where you can consider Sarth's 20% mark his 100% mark. Wipes ending above 20%.. possibly even 15%, that had nothing noticeable go wrong, are actually a long ways away.
I bet sonder's group can do it, especially with Zakili! =P
Also, I'm sure you already know this but I'll state it anyway. Tenebron has to be taunted away at 35% and kited away from the group for several seconds(the longer the better). Perhaps the hunter could accomplish that better for some reason as well. Either way, good luck!