I can imagine your frustration, but let me counter it a bit with a few things to consider:
Let's face it: Endgame is an exclusionist's domain. People calling for higher than practical necessity item levels, that neither convert to or convey actual skill levels, and with recruiting messages like "will kick if you screw up even once".
People bail on LEARNING Parties after even a single wipe, thus making others give up or quit, then no one ends up learning anything. I understand, no one wants to waste their time, but if you don't try, how do you ever learn? Videos aren't a substitute for actual experience.
On the subject of trying, Goblin is apparently one of the smaller population servers, yes. Many players simply haven't TRIED to run Turn 5 for lack of a stable static group, or even just a helpful player who's willing to teach like yourself. It has sadly become accepted standard that if you join a run, EVEN in a learning party, you've either watched a video, attempted it before, or have actually cleared it. This is not true for most Goblin players, myself included. And while I'm confident in my own skills and ability to learn it, many aren't, because they haven't tried. Because they CAN'T try.
Lastly, Art Imitates Life. Yes, it SUCKS when you give your 100% then someone slips up and you all wipe. Personally, I can't stand when there's a slight deviation from plan/strategy and others just STOP DOING ANYTHING and call for a wipe. But, even in real life, someone else's mistake can cost you. It could even kill you. Back in the military, this was what we were taught. How do you fix that? By making sure you're not only good, but your teammate is too. That's how you minimize risks, though even still, anything can happen. Frustrating as it may be, stay the course. If you can do it, show others. Humbly. Patiently. Don't expect ANYONE to clear it the first time, or even immediately after showing them. But be willing to practice with them.
Personally, I want to learn T5, and I would be honored if you'd teach me. I'll give my 100%, I won't quit, and once I know it, I'll turn around and teach others as well, which in hopes would make it easier on you. Find me sometime soon. And let's see if we can't help each other.