Transcript of the above video: 

As the title of this video suggests, we are discussing in the US Immigration context, what are called RFEs, Request for Evidence, versus 221gs, Refusals. What are we talking about here? Well a Request for Evidence is issued when the Department of Homeland Security's adjudicating body i.e. the United States Citizenship and Immigration Service basically in a given petition says "hey we need more information; we need more clarification; we need more documentation." So they issue something called a Request for Evidence. Now in a different phase of the Immigration process, when you are dealing with the US Embassy, they may make a sort of similar request but it's deemed what's called a 221g Refusal. 

Now let me be very clear about something here. 221g Refusals are fundamentally different than RFEs insofar as there are no set rules and regulations exactly regarding how 221gs are issued or administered. So for example, here in Thailand, it is a refusal but it's a refusal pending further documentation. Generally speaking, if you provide said documentation to the satisfaction of the reviewing Consular Officer, they'll go ahead and turn around and approve the case, process out the visa. But note, other jurisdictions other than Thailand, this is a sort of a Thailand specific channel, but other jurisdictions may treat 221gs different. They may treat it as a refusal in its own right and basically send the case back to USCIS for revocation of the underlying approval. Different Embassies do things differently. Here in Thailand though, I think due to a number of different factors including the fact that America's oldest treaty ally in Asia is Thailand, 221gs are not treated with that level of dismissal basically. Basically a 221g represents sort of a final review of the case and basically they say "hey we are missing something, please go ahead and get us that." You are refused a Visa until such time as you remedy the document we're wanting to see or documents or whatever it is they want. You basically give it to him and then the refusal is remedied and it's an approved case. 

Again different Embassies may treat these procedures differently but understand we are talking about this in a purely Thailand context - US Visas coming from Thailand - so the difference being RFEs are issued by the Department of Homeland Security, Requests for Evidence are issued by them. When you are dealing with a 221g, you're going to be dealing with a US Embassy or Consulate outside of the United States.