To mentor people online, one needs to have an online home, this could be a blog where tutorials could be posted; or website for the same purpose.
I simple terms the line of communication between the mentor and the down line should be entirely open to allow easy flow of information.
I also suggest creating a facebook group for your class can also work well to pass on your knowledge.
For video presentations, one can set up a you tube channel for the same purpose.
Hope this helps.