@ Josin - The MD threat doesn't start until the first hunters attack lands, and then it lasts for 4 seconds. So when he said he waited 10 seconds, that was 10 seconds of threat the tank was building before he started doing any damage. In addition, that threat doesn't transfer anywhere, it simply ceases to exist after that 4 seconds.

Regardless, the story sounds iffy to me. If the hunter and tank were the same gear, then the threat mechanics are not so messed up right now that this could have happened as easily as stated. The hunter would have had to crit quite nicely, and the tank would have to have been tanking poorly, especially if the peeled target in question was the primary target. What I think happened was the group was treating the pack ans a pack and not a kill priority list. A few different things may have gone wrong, but this situation would have never happened with a kill prioritization.

IMO, this is a case of using Wrath pack tactics in a Cata/Vanilla world. It simply won't work.

As a DPS, YOU are responsible for your threat, not the tank, or the developers.

It only takes one pull and a glance at Omen to see where you need to set your DPS prioritization to, even if you have to auto-shoot to let the tank build aggro.
The right thing to do is play within the threat mechanics, and skill levels of the players you are provided, and right now, most work just fine if you pay attention.

PS: Although personally I think Prot Warriors and BM Hunters need a little buffing.