Competencies

I am very new to Moodle, i have received a few training courses now and am ready to start building my courses. so far however i have been unable to work this out? I have a mandatory training course (Instructional video) that must be completed by students on an annual basis. On completion of the training they can print out a certificate for their records and for evidence when loading onto a competency database. How can i make the course so they can access again and reattempt the training as if they had never completed before with a new certificate with the correct date? I hope that makes sense?? I have it set at the moment so they must spend 40 minutes on the activity before a certificate will be issued (video is 41 minutes long) The training will be conducted by a lot of people (Potentially 100,000+) so this process needs to be completely automated, also they may access it at any time over the training year. Thanks in advance for any help/guidance you may have