It's interesting the requirement that you have, but classes are just instances of an item instructor led and this is the opposite of the asynchronous learning (eLearnings, videos etc.) which can be launched at any time by the user. From a didactical point of view it makes not much sense to auto-enroll people into classes since you could face a high rate of no shows.
Users are registered into classes by the admin, their manager, or themselves.
Maybe record the class create an Online item with the recording and assign this item to the target population via assignment profile. You could also just assign the Instructor Lead item and inform users to self-register into the existing classes at their choice.