In this vid (http://www.youtube.com/watch?v=txdv_oNq81I) few persons seems not to be so interested about to be tighened on anything, even life, at least from my view. If you are suffering acrofobia, don't watch this.
Added Alternative link (http://www.youtube.com/watch?v=g_hFNjNuGP4)
Another alternative link (http://www.liveleak.com/view?i=07b_1284580365). It seems the activity shown here is against all safety rules, so it's totally going to be deleted, watch it when you can.