What parser are you using to get an overlay like that on the bottom right of your screen?

...doesn't follow a kill order, and keeps on attacking the 35k HP elites exclusively while the 8k HP weaks run amok.

I thought they had disabled augments in PVP because of bolster

As a general rule, main and secondary stats are more important than Endurance, and in regards your particular situation, actually the most important thing for a tank is to a) mitigate incoming damage and b) hold aggro. You mitigate damage by stacking the appropriate tanking stats (defence, shield, absorb) and you hold aggro by building threat on your targets, and for that you will need to hit them as hard as you can, so you will definitely want that aim (more aim = more damage = more threat). In reality, a larger health pool by itself it's not something that is worth going for: the situations where that little extra health actually makes a difference between being dead or alive are a rare exception rather than the rule. And even worse, if you dump your main stat (aim) in lieu of a minuscule amount of health means that you will have a harder time holding aggro, thus making you a sub-par tank. So, in the end, don't worry too much about Endurance. You will get all the Endurance you need as you mod your Trooper. Hope this makes things a little clearer for you. tl;dr: go for your main stat (aim) and your secondary tank stats; Endurance will come by itself.

I think people here have provided you with more than enough advice, so I just want to add this: keep your Veracity Implants.

I've ran tens of flashpoints and got an almost-complete DPS set but only 3 tank pieces or so for my Vanguard. I can't even remember when it was the last time I've seen one drop.

Mercenaries/Commandos don't fare so bad now, but general consensus is that at the moment Snipers are the most OP class when it comes to PVP.

Like the above poster said, it depends on your server. I often read in threads how people say tanks are very scarce, while in Begeren Colony (my server) it's the opposite, for we have a chronic shortage of healers. But generally speaking, you can't go wrong with either.

You can't go wrong with Deep Red / Black

For the same reason we don't have them while most other primates do.

I'm pretty sure the family tree (and the whole Legacy thing) was the brainchild of people who are no longer working on this game, so I doubt we will ever see an update to this feature.

As far as I know those are BiS at the moment because of the high mitigation stats. You can check or ask in the Tanking sub-forum for further reference.

Go buy the Veracity Experimental implants from the GTN, they're better.

At early game it's a real pain to hold aggro given that you don't have as many tools. If even with the ones you have at hand (guard, taunt, aoes, etc.) you find yourself struggling, tell your groupmates to give you an early start to build aggro (2-3 seconds) before joining the fight themselves. This trick it's a little unorthodox but can be very helpful, at every level in fact.

This. This right here. Also, unfortunately a lot of DPS players get tunnel vision and just focus on the mobs ahead and around them, ignoring any sort of kill order and totally oblivious to what goes around them. Also, a lot of them seem to get some strange satisfaction from being able to steal aggro away from the tank.

I just mentioned this on another thread: http://www.swtor.com/community/showthread.php?t=628435

And here I was thinking this right here was the topic of this thread, but from your post and after re-reading the OP I just realised it's a different issue. It happens to me a lot, especially with Ion Pulse, as in OP's video. But that ability delay is still there, and it's not only limited to PVP. So they never solved it (at least not entirely).

It happens to me a lot when using Storm (Vanguard leap). I fire the ability and... nothing. GCD just keeps refreshing as I frantically try to activate other abilities (for some reason this is especially common during Huttball). But the funniest part is that, 4-5 seconds later, my Vanguard will finally leap onto the target, no matter how close or far from it. So now when this happens I try and play with it: it looks so crazy when you land a 40m leap, but it's just so funny when you leap on your target from 1-2m away.