He was up there for about an hour. Chopper circled several times very close.
He’s the only one that you can see, but on a video I have, you can see that there were other people up there but hiding down the spire. Lots and lots of filming was happening—both from the chopper and from below (check out the guy in the cradle hanging lower down the Burj on the left hand side).
They were filming a 360 degree pan of him. My guess is that it’s for promo, and maybe not for the film itself (in all the swinging shots he’s wearing 3/4 length trousers. Here he’s wearing jeans I think).