Generally it's easier to judge the bigger issues on other fights without so much target switching, so if you decide more advice is needed/wanted, post a different fight log too ^^ Looks like on this fight you only made it to the last platform with him, and died during the tiny tentacles. I didn't really look over the first 3min attempt, just looked bad :x
For one thing, he's using Rain of Fire. I don't know why. If it's for the Hemorrhage adds, he should shadowflame and Soulburn: Seed of corruption, then Seed of Corruption till they're dead.
A huge problem I see is that he's not casting Haunt on CD, which is causing his corruption uptime to be much lower than it should be. It keeps falling off, and it should never fall off the primary target to dps. That right there is a huge killer.
Looks like you died to the tiny tentacles on the fourth platform, and overall he did the least damage to them. He is dotting some, but very little damage compare to his SB damage to them. By my math, he got in about 10-15 shadowbolts for 223k and 13k and 28k for corruption and UA, respectively, for BOTH yellow and blue platforms. This means either he's either dotting the one or two which are the first two killed by melee, but more likely he's switching to them very late. From the logs, he was the last to die, but he has only one small tiny mark for having a UA on a tentacle during where you died. Meaning, he is either SBing first THEN dotting (bad, dot first) or not switching to them until everyone else died to only cast one UA.
I'm assuming you're going green - red - yellow - blue. What he needs to do, is probably work on switching to them immediately first, but then dot the ones that appear farthest away first. Those are probably the last ones melee will get too. (all range should really be doing this idea) And then once he's got a dot or two up on two or three of them, forget dotting and start just SBing because by then melee will be moving on to others and wrecking them before your dots do anything.
His use of BoD seems...very weird. It says 28 casts, but it was only a 12min fight, meaning at most....15-18 casts since it's a 1min dot. :O HE CASTED IT ON THE ELEMENTIUM BOLT. TWICE. Slap him for me plz. BoD is one of our most critical and important dots to watch for when it come to casting dots. Generally, you do not want to clip or recast BoD on a different target if you put one up while DS:Felhunter was popped. It can only be on one target, so it must be used wisely. On the first platform, he popped DS and put it on the Arm. Then when DS fell and the mutated corruption spawned, he casted it on the corruption, meaning he made his extra awesome BoD into a normal one (extra awesome because at the start you pre-pot and have every proc proccing). Bad. He did the same thing on the other platforms too, some without DS but same concept. He needs to do one of two things. A) focus the arm/wing and cast BoD on it, then switch to the corruption and use BoA instead until you see that BoD falls off the arm/wing through his focus. At this point, based on corruption health, he will either recast it on the arm or put it on the corruption if the corruption will live for 1min+. B) Do not put BoD on the arm/wing and put BoA at the start of each platform, don't need to focus unless you're double dotting, and then pop DS:Felguard just put up BoD on the corruption.
I recommend A. Either way, once you put up a good BoD, you don't touch that BoD keybind until it is finished or if you have to remove it to prevent it from killing something.
Other than that, his other dot uptimes are pretty good. He could probably squeeze in an extra DS:Felhunter if he casted it more on CD, but that's all judgement based on your target's health and stuff that I can't tell. For the most part, it's not Haunting on CD and bad BoD use that's hurting his self dps, but it's the lack of him getting onto the tentacles that's killing you on the last platform.
---------- Post added 2012-01-19 at 12:04 AM ----------
For demo you want mastery to boot and hands, not haste. You also generally gem int/mastery and not int/haste. For the SB spec, 0/31/10 (your spec), the glyphs are meta/immo/corr. The glyphs you have are for the incin spec, which is very specific spec that I wouldn't recommend ever looking at until you're full BiS and only for Ultrax.
Personally, I recommend going for a haste threshold. You in between the two of them. 1573 for immolate and 1993 for corruption (raid buff with DI and 5% haste). Gives a little umph for multi target fights with the extra ticks.
Other than that, I can't tell you anything else without more info or a log. Those recount images only really tell you did damage and used a pet. Tells nothing about DoT uptime, CD use, or even what pet you had.