Hello all, first of all i want to express deep admiration and gratitude to dosdude and foxlet for their efforts.
i have the same problem with a not working integrated isight camera, and i don't have Virtualbox (and never had). Instead, i had Vmware, wich i have deleted in the hope of solving the problem, but i still haven't a working integrated cam (wich it was working before the instalation of sierra on my unsuported macbook pro 5.2, 17" late 2009).
As it was necessary, i migrated from Snow Leopard, through El Capitan, to Sierra (following all the steps and patches). I did it in a row, so i don't know if the cam was working during the few minutes El Capitan was instaled, so MAYBE it has any relation with something explained on the following site (written for El Capitan):
http://www.insanelymac.com/forum/topic/306777-guide-usb-fix-el-capitan-1011/
Unfortunately, i don't have the knowledge to understand where is the cause for this issue, and i don´t know if there will be further issues to come.
I had to install El Capitan because of the incompatibility of my beloved Snow Leopard and new iOS 10 (and those to come), and now that i have tasted it, for me, it is very convenient to have Sierra because of the copy-paste integration through the i-devices, and the dictation. But i am wondering if there would be better to go back and install El Capitan.
ok, ok, i don't want to nag...
Dosdude, Foxlet, (Anyone!) can help us??