JWs are allowed to take drugs (even things like opiods & marijuana) if they are prescribed by a doctor. This would be "medical" use of drugs.
If they don't have a doctor's prescription but use these drugs anyway, that is "non-medical" or "recreational" use and that will get you DF'ed. Or, as in the case of the convention video, it will prevent you from "qualifying" to be an unbaptized publisher.