Monolingual elicitation–How do you learn a language from someone with whom you don't share a common language?

It's one thing to figure out a foreign language if you are working with an informant who shares some language with you. In that case you can use the shared language to guide your exploration of the foreign language. But what if you're working with an informant where you don't share a language with them? How does it work then? In this video Dan Everett demonstrates.