I work with groupfitlive.com which is a site that does what seems to be exactly what you are looking to do. We look for certified trainers/instructors to create a channel on Group Fit Live where they can post videos for their clients to view. The fees are flexible and we have had great success with the instructors that have enthusiasm and maintain a following from their clients.
This could be a great way for you to get started with your online training!
My e-mail is [email protected]