Is it under copyright or public domain?
Is it fair use?
Is there another exception?
Copyright may be a factor with OWL content, before, during, and after an event. While perhaps not directly applicable to your intended uses, these codes of best practices may help you determine whether or not material can be used, whether access should be open or limited, whether or not it's ok to record the event and post the recording, and what rights you and your presenters may have.