In Southwatch there is a cabin on the mountain (you have to go up the winding path to get there. Inside is an NPC named Beldra Goldhammer. Take her quest.
Link to quest.
After that, you're going to want to go to the light tower you passed while going up the hill, you can actually drop from the griffon where you turned in the last quest. Once you get to that tower, go inside, and there will be Ama Mullen with a quest. Get that quest, and complete it
Link to quest.
After you killed all the ridgefury things and have their hides, take them back, turn them in, and go back to Beldra Goldhammer. She will give you a quest called Slay the Silvertalon Pride. DO NOT COMPLETE IT...EVER!!!
She will give you a no rent flying mount (griffon) that you can only summon around the other griffons where you turned in the first quest. Be vary careful because once you summon it you can only go so far away before it poofs.
Now for the exploit....
All you have to do is summon the griffon, start flying (double jump, the controls are just like swimming) and start flying up the mountain. Make sure you don't touch the ground or you'll stop flying. Just throw auto run on (haven't tried it without it) and keep flying up the hill. You'll chunk, have no griffon, but will still be able to fly where ever you want! You can chunk while doing it and keep the effect, I flew from Southwatch to the Deebs and back.
It makes it easy for casters to kill stuff without getting hit too! since you can be out of melee range and still cast! The quest, has an hour timer, but you can just abandon the quest and keep flying too!
One note....Don't touch water or summon your mount, it'll take the bug off. But you can use sprint and other run speed buffs!!
I hope this is good enough for a free premium membership.
Good luck, and if you have problems, just PM me.