Currently, Leanpub courses only support unlisted (and public) YouTube videos. You cannot include videos in your course by uploading them to Leanpub in our Browser writing mode, or by uploading them to your
resources folder in our other writing modes, sorry about that.
Unlisted YouTube videos can be found by people who have not bought your course. Our opinion on this matter is that as a content creator, the real threat is that nobody wants to read or watch your stuff, and anyone who finds the course independently may be encouraged to then buy the course, when they may not have bought it otherwise. (For a much longer explanation of our position on this kind of thing generally, please see this book.)