No holds barred set of linguistics lectures from author and linguist John McWhorter.
These lectures are different from other TTC language offerings in that McWhorter spends as much time in the present as he does dealing with the history of human languages.
Creoles (his specialty), pidgins, artificial languages, and even sign languages all get their due in this series.
Throughout, McWhorter delivers dense information with honesty, forsaking "political correctness", and with wit, making what could be a dry subject into an engrossing listening experience.
There are twelve lectures in all, dealing with subjects ranging from proto-languages, language acquisition, and unnatural grammar rules. A detailed and thorough study guide accompanies the audio portion of this set.
Irregardless of his credentials, I think he is mistaken in his view of grammar.