Certainly non-Jews have been performing at Orthodox Jewish weddings for years. Some of the more notable ones: Carmine D' Amico (now in Arizona), Mat Hill, George Hooks, Ron Bertolet etc. but it's quite unusual to ever see a non-Jew being allowed to sing (let alone one that would know how) at a religious Jewish wedding.
It first started out as a you tube video filmed by Eitan Katz here. Well now it seems that Nolan Jackson got his chance to sing "Binyan Adei Ad" at an actual Jewish wedding. As you can see someone is trying to convert him by putting a black hat on his head. There is a certain level of "shtick" to the whole performance. I'm certain there are some who would certainly not approve. Of course the other side would say you have non-Jews playing...why can't they sing too? What do you make of it?