For the purpose of general discussion about Crash Course's offerings, the delivery model or any other issues related to how Crash Course is writing and publishing online training, I've created the Mailman-based mailing list
firstname.lastname@example.org, which is open to the public and which you can subscribe to by sending a short "subscribe" message to the address
email@example.com (as long as I've managed to create and configure that correctly).
Let me emphasize that this list is a general list for wide-ranging discussions about course design in general, suggestions for future courses, comments about the delivery model and the like, and is open to absolutely anyone, registered student or not.
It is not for discussions specific to a single course. Each Crash Course offering will have its own course-specific mailing list that will be available only to registered students of that course. Consider that one of the benefits of registration.