Do The Impossible, indeed. Looping a thin thread over someone's head several meters away is tricky business. The slightest bit of wind throws it off. And this must be done without moving the wand or betraying the operation through one's facial expression. I can't imagine it being done without the utmost concentration, allowing of course for effort to be expended talking to Voldemort and maintaining mental blocks against any Legilimens among the Death Eaters (recall that in Half-Blood Prince Snape was able to detect spells forming in Harry's mind). This is all done perfectly the first time around. Thirty-six times, plus Voldemort's wrists.

I suppose one can honestly say A Wizard Did It...