Basicly I was lagging (couldn't see some vendors and people) then i jumped up in the air and dismounted,
I just hovered on the air, so i turn around with "a" and I stood in middle air.
Rinse and repeat and i was high up on the air.
I was also able to enter the hordes tent o_0.
EDIT: With this, i was able to get on top of Ulduar with a chopper. Appearently, it has epic utilities!
Video (laggy?):
YouTube - Argent tournament bug