I searched around for a bit on the forum, and surprisingly I found nothing about it, so here goes..
Molten Core Exploit - YouTube
Please watch the video before reading on.
Some of you might say that this exploit is useless, since you can just complete the quest and teleport directly into Molten Core... Well here's why you're wrong:
When you teleport into MC by speaking to Lothos Riftwaker, you enter the raid with your "own" raid save, meaning that even if someone in your group were to talk to Lothos Riftwaker aswell, you would not end up in the same raid save.
Whereas if you were to use this method, it would basically be a neat little teleport for everyone directly into MC. And everyone in your group will end up in the same raid save.
Using this exploit requires you to be in a raid group.