If I'm not mistaken, I wrote quite a bit about Archbishop George Alexander McGuire and the African Orthodox Church some years ago, either here or at ByzCath - I'd have to go hunting. McGuire did indeed receive episcopal orders from Joseph Rene Vilatte, who had his own orders from the Syriac Orthodox.
Vilatte is near the base of the episcopal family tree of most every vagante bishop to be found who claims to head a 'Church' that is of the so-called 'independent' Catholic/Orthodox, or both persuasion.
As to whether there is any validity to the episcopal orders (or even the presbyteral orders) that he conferred - it comes down to whether the Cyprianic or Augustinian view is held by the Church being queried on the point.
Historically, the Eastern Orthodox view - the Cyprianic theory - would accord no sacramental grace to the orders that he conferred. The Catholic view - the Augustinian theory to which it long held, but from which it now seems to be backing away - would have accorded sacramental grace to at least Vilatte's conferral of such. Most Oriental Orthodox, otoh, have traditionally been less rigid on the matter than either the Eastern Orthodox or the Catholics and have gone both ways on the issue.
My recollection is that, in a discussion between Phil/Mor Ephrem and myself, some years ago, he suggested that Vilatte's own orders were generally viewed to be valid by his Church, but he was less sure what view was taken toward those on whom he subsequently conferred orders.
If anyone really wants to delve into Vilatte or McGuire, I'll go digging, but I think it's all been said before.