Just as a side note, I looked at the priest's spec, and it's kinda weird. I haven't played my priest in about 3 months or so, but even so. 4/5 in silent resolve? I think 4% threat reduction isn't something to laugh at.
Also I don't see the value in mental agility (reduce mana cost of insta-casts by 10%) You might as well just spend 2 talent points in healing prayers which reduces the cost of prayer of mending (a priest's bread and butter instant) and prayer of healing by 20%. 5 talent points for a miniscule amount of mana off from your dispels and such is really not worth it. With his gear set I don't think imp Divine Spirit is a good choice either... Just my two cents about the priest, and yes I know he wasn't the problem.
Anyway as a hunter, it's always fun to try and see how much threat you can produce. I always had fun FD'ing and then seeing how fast I could climb the meter, but you should always be aware of when you're about to draw aggro. When you play a class long enough you just get a feel for when you should FD or whatever aggro dump you have. Personally I never really look at the threat meters in raids. If you see a long string of crits or such then yes, you FD. You have to have a feel for your class.
As for yourself losing your temper, I do it all the time. That's why I'm poor. I keep getting fed up and respecing to ret and then back to prot
Looking at the hunter's gear, he needs to gem and enchant differently. He seems to be stacking AP when his crit rate isn't that high. My suggestion to him would be to stack agi. For hunters agi will almost always be better than straight AP. 1 point of agi is worth 1 Ap and some crit (sorry, i forget off the top of my head). Also agi scales with kings, unlike AP. Also his enchants are stamina a lot and savagery on his weapon. Again he should be going for Agi, or at least AP, but not stam. His spec is ok. There's a few iffy choices though. Spirit bond is a weak pve talent (2% health regen every 10 seconds), as is the point in thick hide. If he's worried about mend pet (he put one point in there) he could easily put a point from spirit bond in there and put the other one and the one from thick hide into endurance training (2% extra health for him and 4% for his pet)
*EDIT*
Also the hunter should not be using that bow. It's too fast for a good rotation BM spec. Optimal speed is a 2.8 bow such as Valanos' Longbow. There's an abundance of them on most servers, so they're not hard to get. He could put a hit or crit scope on it, optimally hit. Definitely not a +dmg scope though. It's arguably the best bow you can get before steelhawk and then wolfslayer's in Kara. With the 2.8 speed bow he should be able to get a 3:2 rotation in which will do more damage than a 1:1.
Sorry for all the hunter-crafting and such... Once a hunter, always a hunter.