So me and my mate was playing on the school some time ago and found this totally random when our teacher raged and pulled the internet, been holding this exploration in for some while since I was sure someone had found it, but looked around yesterday so I give it a shot, if its a repost please give a link aswell.
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There is the video, but I give a fast explanation anyway.
Start out by taking the zepp from Orgrimmar heading for Borean Tundra,
Then when you get there mount up and fly heading to Grizzly hills WITHOUT touching the ground, if you do you have to start over.
Next when you get there you fly pretty high above Ursoc's Den then DC by pulling internet cable of simply just disconnecting your internet, next thing you know you're under Hyjal and just fly up and you'll be there.
If you fail on first try at DC part you can still try again if youhaven't landed yet.