Many Dopers will enjoy the forty-odd short (5- to 15-minute) YouTube video lessons by NativLang, all about languages. They’re fun and informative (though the presenter’s forced chuckle occasionally grates). In the “Caucasus: Mountains Full of Languages,” he gives a shout-out to our own Johanna Nichols, when explaining the geographic factors behind the Caucasus’ linguistic diversity.
I fully recommend NativLang. It’s fantastic.