Here is what the US Embassy says and for some reason there in disagreement with the FB Experts.
Embassies and Consulates cannot perform or register marriages. The following information is provided:
A legal marriage in Thailand consists of two parties registering their union with a local Amphur (Thai district office, similar to a county office). It is a process that can take several days to complete.
****************************************************************************************************************************
%20and%20Consulates%20cannot%20perform,take%20several%20days%20to%20complete.